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| Titel |
One-year observations of carbonaceous and nitrogenous components and major ions in the aerosols from subtropical Okinawa Island, an outflow region of Asian dusts |
| VerfasserIn |
B. Kunwar, K. Kawamura |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 4 ; Nr. 14, no. 4 (2014-02-17), S.1819-1836 |
| Datensatznummer |
250118407
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| Publikation (Nr.) |
 copernicus.org/acp-14-1819-2014.pdf |
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| Zusammenfassung |
| Ambient aerosol samples (TSP, n = 50) were collected for 12 months at
subtropical Okinawa Island, Japan, an outflow region of Asian dusts in the
western North Pacific and analysed for organic carbon (OC), elemental carbon
(EC), water-soluble organic carbon (WSOC), water-soluble total nitrogen
(WSTN), water-soluble organic nitrogen (WSON) and major ions to better
understand the formation and transformation of East Asian aerosols during
long-range atmospheric transport. Concentration ranges of these components
are; OC: 0.76–7.1 μg m−3 (av. 1.7 ± 1.0 μg m−3), EC:
0.07–0.96 μg m−3 (0.28 ± 0.19 μg m−3),
WSOC: 0.27–1.9 μg m−3
(0.73 ± 0.38 μg m−3), WSTN: 0.77 to
3.0 μg m−3 (0.58 ± 0.46 μg m−3) and
WSON: 0.0–2.2 μg m−3
(0.12 ± 0.23 μg m−3). Higher OC concentrations were
obtained in active biota seasons; spring (av. 2.4 μg m−3) and
summer (1.8 μg m−3). EC and WSOC concentrations maximized in
spring (av. 0.41 μg m−3 and 0.95 μg m−3,
respectively) followed by winter (0. 70 and 0.90 μg m−3)
whereas they became lowest in summer (0.19 and 0.52 μg m−3).
In contrast, WSTN concentrations were highest in winter
(0.86 μg m−3) and lowest in summer
(0.37 μg m−3) and autumn (0.34 μg m−3).
Concentrations of WSON are higher in early summer (av.
0.26 μg m−3) due to the emission from marine biota. The high
ratios of OC / EC (av. 7.6) and WSOC / OC (44%) suggest a secondary
formation of organic aerosols. Strong correlation between OC and MSA-
(0.81) in spring suggests that springtime aerosols are influenced by
additional marine and terrestrial biogenic sources. The positive correlation
of Ca2+ and TSP in spring (r = = 0.81) demonstrates a significant
contribution of Asian dust whereas high abundances of NO3- and
nss-SO42- in winter suggest an important contribution from
anthropogenic sources including biomass burning, vehicular emission and coal
combustion. NH4-N/WSTN ratios peaked in winter (0.56), indicating a
significant contribution of biomass burning to WSTN in cold season. In
contrast, higher NO3-N/WSTN ratio in spring than winter suggests that the
atmospheric transport of vehicular emissions maximizes in spring. Correlation
analyses of major ions suggest that NH4+ and Ca2+ play major
role in the neutralization of acidic aerosols forming NH4HSO4,
(NH4)2SO4 and CaSO4. |
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