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| Titel |
Size distribution of PM at Cape Verde - Santiago Island |
| VerfasserIn |
C. Pio, T. Nunes, J. Cardoso, A. Caseiro, M. Cerqueira, D. Custódio, M. C. Freitas, S. M. Almeida |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250070980
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| Zusammenfassung |
| The archipelago of Cape Verde is located on the eastern North Atlantic, about 500 km west of
the African coast. Its geographical location, inside the main area of dust transport over
tropical Atlantic and near the coast of Africa, is strongly affected by mineral dust from the
Sahara and the Sahel regions.
In the scope of the CVDust project a surface field station was implemented in the
surroundings of Praia City, Santiago Island (14Ë 55’ N e 23Ë 29’ W, 98 m at sea level),
where aerosol sampling throughout different samplers was performed during one
year.
To study the size distribution of aerosol, an optical dust monitor (Grimm 180), from 0.250
to 32 μm in 31 size channels, was running almost continuously from January 2011 to
December 2011. The performance of Grimm 180 to quantify PM mass concentration in an
area affected by the transport of Saharan dust particles was evaluated throughout the
sampling period by comparison with PM10 mass concentrations obtained with the
gravimetric reference method (PM10 TSI High-Volume, PM10 Partisol and PM10
TCR-Tecora).
PM10 mass concentration estimated with the Grimm 180 dust monitor, an optical counter,
showed a good correlation with the reference gravimetric method, with R2= 0.94 and a linear
regression equation of PM10Grimm = 0.81PM10TCR- 5.34.
The number and mass size distribution of PM at ground level together with
meteorological and back trajectories were analyzed and compared for different
conditions aiming at identifying different signatures related to sources and dust
transport.
January and February, the months when most Saharan dust events occurred, showed the
highest concentrations, with PM10 daily average of 66.6±60.2 μg m-3 and 91.6±97.4 μg
m-3, respectively. During these months PM1 and PM2.5 accounted for less than 11% and
47% of PM10 respectively, and the contribution of fine fractions (PM1 and PM2.5) to PM
mass concentrations tended to increase for the other months. During Saharan dust events, the
PM2.5 hourly average could reach mass concentrations higher than 200 μg m-3 whereas
PM10 overpass 600 μg m-3.
Acknowledgement: This work was funded by the Portuguese Science Foundation (FCT)
through the project PTDD/AAC-CLI/100331/2008 and FCOMP-01-0124-FEDER-008646
(CV-Dust). J. Cardoso acknowledges the PhD grant SFRH-BD-6105-2009 from FCT. |
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