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| Titel |
Mass concentrations of black carbon measured by four instruments in the middle of Central East China in June 2006 |
| VerfasserIn |
Y. Kanaya, Y. Komazaki, P. Pochanart, Y. Liu, H. Akimoto, J. Gao, T. Wang, Z. Wang |
| 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 ; 8, no. 24 ; Nr. 8, no. 24 (2008-12-18), S.7637-7649 |
| Datensatznummer |
250006524
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| Publikation (Nr.) |
 copernicus.org/acp-8-7637-2008.pdf |
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| Zusammenfassung |
| Mass concentrations of black carbon (BC) were determined in June 2006 at the
top of Mount Tai (36.26° N, 117.11° E, 1534 m a.s.l.), located in the
middle of Central East China, using four different instruments: a
multi-angle absorption photometer (5012 MAAP, Thermo), a particle soot
absorption photometer (PSAP, Radiance Research), an ECOC semi-continuous
analyzer (Sunset Laboratory) and an Aethalometer (AE-21, Magee Scientific).
High correlation coefficients (R2>0.88) were obtained between the
measurements of the BC mass concentrations made using the different
instruments. From the range of the slopes of the linear least-square
fittings, we concluded that BC concentrations regionally-representative of
the area were measured in a range with a maximum-to-minimum ratio of 1.5 (an
exception was that the BC (PM2.5) concentrations derived from MAAP were
~2 times higher than the optical measurements (PM2.5) derived
from the ECOC analyzer). While this range is significant, it is still
sufficiently narrow to better constrain the large and highly uncertain
emission rate of BC from Central East China. In detail, two optical
instruments (the MAAP and the PSAP equipped with a heated inlet 400°C)
tended to give higher concentrations than the thermal EC concentrations
observed by the ECOC analyzer. The ratios of optical BC to thermal EC showed
a positive correlation with the OC/EC ratio reported by the ECOC analyzer,
suggesting two explanations. One is that the optical instruments
overestimated BC concentrations in spite of careful cancellation of the
scattering effect in the MAAP instrument and the expected evaporation of
volatile species by heating the inlet of the PSAP instrument. The other is
that the determined split points between OC and EC were too late when a
large amount of OC underwent charring during the analysis, resulting in an
underestimation of EC by the ECOC analyzer. High ratios of optical BC to
thermal EC were recorded when the NOx/NOy ratio was low, implying
the coating of the particles became thicker in an aged air mass and thus
resulted in the optical instruments overestimating BC concentrations because
of the lensing effect. |
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