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Rai P, Furger M, El Haddad I, Kumar V, Wang L, Singh A, Dixit K, Bhattu D, Petit JE, Ganguly D, Rastogi N, Baltensperger U, Tripathi SN, Slowik JG, Prévôt ASH. Real-time measurement and source apportionment of elements in Delhi's atmosphere. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 742:140332. [PMID: 33167294 DOI: 10.1016/j.scitotenv.2020.140332] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/16/2020] [Accepted: 06/16/2020] [Indexed: 05/05/2023]
Abstract
Delhi, the capital of India, suffers from heavy local emissions as well as regional transport of air pollutants, resulting in severe aerosol loadings. To determine the sources of these pollutants, we have quantified the mass concentrations of 26 elements in airborne particles, measured by an online X-ray fluorescence spectrometer with time resolution between 30 min and 1 h. Measurements of PM10 and PM2.5 (particulate matter <10 μm and < 2.5 μm) were conducted during two consecutive winters (2018 and 2019) in Delhi. On average, 26 elements from Al to Pb made up ~25% and ~19% of the total PM10 mass (271 μg m-3 and 300 μg m-3) in 2018 and 2019, respectively. Nine different aerosol sources were identified during both winters using positive matrix factorization (PMF), including dust, non-exhaust, an S-rich factor, two solid fuel combustion (SFC) factors and four industrial/combustion factors related to plume events (Cr-Ni-Mn, Cu-Cd-Pb, Pb-Sn-Se and Cl-Br-Se). All factors were resolved in both size ranges (but varying relative concentrations), comprising the following contributions to the elemental PM10 mass (in % average for 2018 and 2019): Cl-Br-Se (41.5%, 36.9%), dust (27.6%, 28.7%), non-exhaust (16.2%, 13.7%), S-rich (6.9%, 9.2%), SFC1 + SFC2 (4%, 7%), Pb-Sn-Se (2.3%, 1.66%), Cu-Cd-Pb (0.67%, 2.2%) and Cr-Ni-Mn (0.57%, 0.47%). Most of these sources had the highest relative contributions during late night (22:00 local time (LT)) and early morning hours (between 03:00 to 08:00 LT), which is consistent with enhanced emissions into a shallow boundary layer. Modelling of airmass source geography revealed that the Pb-Sn-Se, Cl-Br-Se and SFC2 factors prevailed for northwest winds (Pakistan, Punjab, Haryana and Delhi), while the Cu-Cd-Pb and S-rich factors originated from east (Nepal and Uttar Pradesh) and the Cr-Ni-Mn factor from northeast (Uttar Pradesh). In contrast, SFC1, dust and non-exhaust were not associated with any specific wind direction.
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Affiliation(s)
- Pragati Rai
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Markus Furger
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
| | - Imad El Haddad
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Varun Kumar
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Liwei Wang
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Atinderpal Singh
- Geosciences Division, Physical Research Laboratory, Ahmedabad 380009, India
| | - Kuldeep Dixit
- Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Deepika Bhattu
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Jean-Eudes Petit
- Laboratoire des Sciences du Climat et l'Environnement, CEA/Orme des Merisiers, 91191 Gif-sur-Yvette, France
| | - Dilip Ganguly
- Centre for Atmospheric Sciences, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Neeraj Rastogi
- Geosciences Division, Physical Research Laboratory, Ahmedabad 380009, India
| | - Urs Baltensperger
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Sachchida Nand Tripathi
- Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India.
| | - Jay G Slowik
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - André S H Prévôt
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
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