Source characterization of volatile organic compounds measured by PTR-ToF-MS in Delhi, India
Abstract
Volatile organic compounds (VOCs) are important trace gas constituents in the troposphere, impacting local and regional air quality, human health, and climate both directly and indirectly (IPCC, 2013). Delhi, the capital city of India, with a population of 18.98 million (2012) people, has air quality ranked as the worst among 1600 major cities around the world (WHO, 2015). However, information on pollution levels, VOC emission inventories, and their sources in Delhi is still lacking. In this study, we report simultaneous on-line measurements of VOCs in Delhi, India at two separate sites (urban and suburban), utilizing the PTR-ToF-MS 8000. Very high VOC mixing ratios and strong diurnal patterns were observed at both sites, in particular at the urban site. To determine the origins of the VOCs, the positive matrix factorization (PMF) receptor model was applied to data from each site separately, and six major source factors were identified at both sites: two factors from traffic related emissions, two from solid fuel combustion, and two secondary VOC factors. Among them, anthropogenic activities are important VOC sources in both the urban and suburban area. Traffic related emissions were dominant at both sites, while solid fuel combustion contributed significantly to the total nocturnal VOC mixing ratio. During the daytime, however, higher contributions were found from the secondary factors, which are dominated by oxygenated VOCs. Although the factor profiles were similar for the primary factors at the two sites, their diurnal patterns were very different. Compared to the suburban site, much higher nocturnal concentrations and day-night variations were observed at the urban site. The secondary factors, however, differed between the two sites in terms of both composition and diurnal patterns. In addition, a comparison of the diurnal cycles of selected markers indicates that distinct differences exist in concentrations, variations and source contributions of certain VOCs.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A51C..04W
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0317 Chemical kinetic and photochemical properties;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0345 Pollution: urban and regional;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSES