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| Titel |
Temporal variability in aerosol composition at an urban site, Varanasi in the eastern Indo-Gangetic Plain |
| VerfasserIn |
Kirpa Ram, Stefan Norra, Chen Yuan, Rangu Venkata Satish, Neeraj Rastogi |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250138309
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| Publikation (Nr.) |
 EGU/EGU2017-1285.pdf |
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| Zusammenfassung |
| PM2.5 aerosol samples (n=31) were collected from an urban site, Varanasi (25∘ 28’N, 83∘0’
E) in the eastern Indo-Gangetic Plain during May 2015 to March 2016 using a mini-volume
sampler (Leckel GmbH, Germany) at a flow rate of 200 l/hr. The PM2.5 samples were
integrated for 7 days and were analyzed for organic and elemental carbon (OC & EC),
water-soluble OC (WSOC), organic and inorganic nitrogen (ON & IN) and water-soluble
inorganic species (WSIS) to study the geochemical behavior of aerosols. The mass
concentration of OC and EC varies from 4.2 to 105.2 (average: 32.8) μg m-3 and 1.2 to 7.0
(average: 4.6) μg m-3 during the study period with total carbonaceous aerosols
(TCA=1.6*OC+EC), on an average, accounting for ∼59% of PM2.5 mass. Relatively high
WSOC/OC ratio (average: 0.55±0.18; range 0.18-0.86) indicate a significant contribution
from the secondary organic aerosols at Varanasi. The concentration of ON varies from less
than detection limit to 5.3 (average: 2.4) μg m-3 which contribute to ∼12% of WSOC
highlighting the presence of nitro-organic compounds in aerosols at Varanasi. The
average WSIS contribution to PM2.5 is only 17% with a strong seasonal variability
(range: 4-36%). Generally, carbonaceous and inorganic aerosol concentration is
higher during winter, fall and post-monsoon that those in the summer when dust
aerosol contribution is significant (as high as 75% of PM2.5 mass). This study
highlights the role of nitro-organic compounds in secondary organic aerosols which
is lacking in Indian aerosols. Furthermore, these aerosol samples could be very
important for the study of particle morphology and composition using scanning-electron
Microscope-Energy Dispersive X-ray due to lower impaction in the mini-volume sampler. |
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