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| Titel |
Carbonaceous aerosols on the south edge of the Tibetan Plateau: concentrations, seasonality and sources |
| VerfasserIn |
Z. Cong, S. Kang, K. Kawamura, B. Liu, X. Wan, Z. Wang, S. Gao, P. Fu |
| 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 ; 15, no. 3 ; Nr. 15, no. 3 (2015-02-13), S.1573-1584 |
| Datensatznummer |
250119409
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| Publikation (Nr.) |
 copernicus.org/acp-15-1573-2015.pdf |
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| Zusammenfassung |
| To quantitatively evaluate the effect of carbonaceous aerosols on the south
edge of the Tibetan Plateau, aerosol samples were collected weekly from
August 2009 to July 2010 at Qomolangma (Mt. Everest) Station for Atmospheric and Environmental
Observation and Research (QOMS, 28.36° N,
86.95° E, 4276 m a.s.l.). The average concentrations of organic
carbon (OC), elemental carbon (EC) and water-soluble organic carbon were 1.43, 0.25 and 0.77 μg m−3, respectively. The
concentration levels of OC and EC at QOMS are comparable to those at high-elevation sites on the southern slopes of the Himalayas (Langtang and
Nepal Climate Observatory at Pyramid, or NCO-P), but 3 to 6 times lower than those at Manora Peak, India, and
Godavari, Nepal. Sulfate was the most abundant anion species followed by
nitrate, accounting for 25 and 12% of total ionic mass, respectively.
Ca2+ was the most abundant cation species (annual average of 0.88 μg m−3). The dust loading, represented by Ca2+ concentration, was
relatively constant throughout the year. OC, EC and other ionic species
(NH4+, K+, NO3− and SO42−) exhibited a
pronounced peak in the pre-monsoon period and a minimum in the monsoon
season, being similar to the seasonal trends of aerosol composition reported
previously from the southern slope of the Himalayas, such as Langtang and
NCO-P. The strong correlation of OC and EC in QOMS aerosols with K+ and
levoglucosan indicates that they mainly originated from biomass
burning. The fire spots observed by MODIS and backward air-mass trajectories
further demonstrate that in pre-monsoon season, agricultural and forest
fires in northern India and Nepal were most likely sources of
carbonaceous aerosol at QOMS. Moreover, the CALIOP observations confirmed
that air-pollution plumes crossed the Himalayas during this period. The
highly coherent variation of daily aerosol optical depth (500 nm)
between QOMS and NCO-P indicates that both slopes of the Himalayas share a
common atmospheric environment regime. In addition to large-scale
atmospheric circulation, the unique mountain/valley breeze system can also
have an important effect on air-pollutant transport. |
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