Journal article
Wintertime Air Quality in Lumbini, Nepal: Sources of Fine Particle Organic Carbon
ACS earth and space chemistry, Vol.5(2), pp.226-238
02/18/2021
DOI: 10.1021/acsearthspacechem.0c00269
Abstract
The Indo-Gangetic Plains (IGP) experience high levels of airborne particulate matter (PM), especially during the dry season. Contributing to PM are natural and anthropogenic emissions and the atmospheric transformation of gases to form particles. Regional smog events occur frequently during wintertime and provide an atmospheric medium for aerosol processing. Here, we investigate the chemical composition and sources of PM at a representative site in the northern IGP during the second Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE 2). In Lumbini, Nepal, the 24 h average PM2.5 and PM10 concentrations ranged 48-295 and 60-343 μg m-3, respectively, from December 20, 2017, to January 1, 2018. On average (± standard deviation), PM2.5 was composed of 39 ± 7% organic carbon (OC), 5 ± 2% elemental carbon (EC), and 20 ± 6% secondary inorganic ions (ammonium, nitrate, and sulfate), 2.0% chloride, and 1.3% potassium. Biomass burning was a major PM source, indicated by a median levoglucosan concentration of 3.5 μg m-3. Secondary organic aerosol (SOA) derived from biomass burning was indicated by high concentrations of nitromonoaromatic compounds (e.g., 4-nitrocatechol peaking at 435 ng m-3). During periods of fog, characterized by high relative humidity (RH) and relatively low solar radiation, nitroaromatic concentrations dropped despite levoglucosan remaining high, indicating that their formation was suppressed. Chemical signatures of SOA indicated that volatile organic compound (VOC) precursors were primarily combustion-derived, with small contributions from biogenic VOC. Through molecular markers and chemical mass balance (CMB) modeling, sources of PM2.5 OC were identified as cow dung burning (24 ± 16%), other biomass burning (20 ± 7%), plastic/garbage burning (4.7 ± 3.2%), vehicle emissions (3.1 ± 1.4%), coal combustion (0.3 ± 0.2%), and SOA from monoaromatic VOC (4.1 ± 0.8%), diaromatic VOC (8.9 ± 4.0%), cresol (0.3 ± 0.4%), isoprene (0.4 ± 0.2%), monoterpenes (1.5 ± 0.6%), and sesquiterpenes (3.2 ± 0.7%). Understanding the levels of PM in Lumbini, along with its chemical composition and sources of OC, contributes to a better understanding of regional air quality episodes in the IGP.
Details
- Title: Subtitle
- Wintertime Air Quality in Lumbini, Nepal: Sources of Fine Particle Organic Carbon
- Creators
- Md. Robiul Islam - Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United StatesTianyi Li - Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United StatesKhadak Mahata - Alpine Consultancy, Kathmandu 44600, NepalNita Khanal - Alpine Consultancy, Kathmandu 44600, NepalBenjamin Werden - Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, Maryland 21205, United StatesMichael R Giordano - OSU-EFLUVE, LISA-CNRS, UPEC, Cŕteil 94000, FranceP. S Praveen - International Centre for Integrated Mountain Development (ICIMOD), Lalitpur, Kathmandu 44700, NepalNarayan Babu Dhital - Tribhuvan University, Patan Multiple Campus, Lalitpur Kathmandu 44700, NepalAnobha Gurung - Clean Cooking Alliance, Washington, D. C. 20006, United StatesArnico K Panday - International Centre for Integrated Mountain Development (ICIMOD), Lalitpur, Kathmandu 44700, NepalIndu Bikram Joshi - Department of Environment, Ministry of Forests and Environment, Kathmandu 44600, NepalShankar Prasad Poudel - Department of Environment, Ministry of Forests and Environment, Kathmandu 44600, NepalYanbo Wang - Department of Computer Science, Emory College of Arts and Sciences, Atlanta, Georgia 30322, United StatesEri Saikawa - Department of Environmental Sciences, Emory University, Atlanta, Georgia 30322, United StatesRobert J Yokelson - Department of Chemistry, University of Montana, Missoula, Montana 59812, United StatesPeter F DeCarlo - Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, Maryland 21205, United StatesElizabeth A Stone - Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States, Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, Iowa 52242, United States
- Resource Type
- Journal article
- Publication Details
- ACS earth and space chemistry, Vol.5(2), pp.226-238
- DOI
- 10.1021/acsearthspacechem.0c00269
- ISSN
- 2472-3452
- eISSN
- 2472-3452
- Grant note
- DOI: 10.13039/100000159, name: Division of Atmospheric and Geospace Sciences, award: AGS-1349976, AGS-1350021, AGS-1351616, AGS-1461458
- Language
- English
- Date published
- 02/18/2021
- Academic Unit
- Chemistry; Chemical and Biochemical Engineering
- Record Identifier
- 9984216674102771
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