Journal article
Submicron Aerosol Composition and Source Contribution across the Kathmandu Valley, Nepal, in Winter
ACS earth and space chemistry, Vol.7(1), pp.49-68
01/19/2023
DOI: 10.1021/acsearthspacechem.2c00226
Abstract
The Kathmandu valley experiences an average wintertime PM1 concentration of ∼100 μg m–3 and daily peaks over 200 μg m–3. We present ambient nonrefractory PM1 chemical composition, and concentration measured by a mini aerosol mass spectrometer (mAMS) sequentially at Dhulikhel (on the valley exterior), then urban Ratnapark, and finally suburban Lalitpur in winter 2018. At all sites, organic aerosol (OA) was the largest contributor to combined PM1 (C-PM1) (49%) and black carbon (BC) was the second largest contributor (21%). The average background C-PM1 at Dhulikhel was 48 μg m–3; the urban enhancement was 120% (58 μg m–3). BC had an average of 6.1 μg m–3 at Dhulikhel, an urban enhancement of 17.4 μg m–3. Sulfate (SO4) was 3.6 μg m–3 at Dhulikhel, then 7.5 μg m–3 at Ratnapark, and 12.0 μg m–3 at Lalitpur in the brick kiln region. Chloride (Chl) increased by 330 and 250% from Dhulikhel to Ratnapark and Lalitpur on average. Positive matrix factorization (PMF) identified seven OA sources, four primary OA sources, hydrocarbon-like (HOA), biomass burning (BBOA), trash burning (TBOA), a sulfate-containing local OA source (sLOA), and three secondary oxygenated organic aerosols (OOA). OOA was the largest fraction of OA, over 50% outside the valley and 36% within. HOA (traffic) was the most prominent primary source, contributing 21% of all OA and 44% of BC. Brick kilns were the second largest contributor to C-PM1, 12% of OA, 33% of BC, and a primary emitter of aerosol sulfate. These results, though successive, indicate the importance of multisite measurements to understand ambient particulate matter concentration heterogeneity across urban regions.
Details
- Title: Subtitle
- Submicron Aerosol Composition and Source Contribution across the Kathmandu Valley, Nepal, in Winter
- Creators
- Benjamin S. Werden - Drexel UniversityMichael R. Giordano - Drexel UniversityKhadak Mahata - International Centre for Integrated Mountain DevelopmentMd. Robiul Islam - Department of Chemistry, University of Iowa, 230 North Madison Street, Iowa City, Iowa52242-1294, United StatesJ. Douglas Goetz - Drexel UniversitySiva Praveen Puppala - International Centre for Integrated Mountain DevelopmentEri Saikawa - Emory UniversityArnico K. Panday - International Centre for Integrated Mountain DevelopmentRobert J. Yokelson - University of MontanaElizabeth A. Stone - Department of Chemistry, University of Iowa, 230 North Madison Street, Iowa City, Iowa52242-1294, United StatesPeter F. DeCarlo - Drexel University
- Resource Type
- Journal article
- Publication Details
- ACS earth and space chemistry, Vol.7(1), pp.49-68
- DOI
- 10.1021/acsearthspacechem.2c00226
- ISSN
- 2472-3452
- eISSN
- 2472-3452
- Grant note
- DOI: 10.13039/100000159, name: Division of Atmospheric and Geospace Sciences, award: AGS 1349967, AGS 1351616, AGS 1461458
- Language
- English
- Electronic publication date
- 12/08/2022
- Date published
- 01/19/2023
- Academic Unit
- Chemistry; Chemical and Biochemical Engineering
- Record Identifier
- 9984339356202771
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