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| Titel |
Aerosol size-resolved trace metal composition in remote northern tropical Atlantic marine environment: case study Cape Verde islands |
| VerfasserIn |
K. W. Fomba, K. Müller, D. Pinxteren, H. Herrmann |
| 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 ; 13, no. 9 ; Nr. 13, no. 9 (2013-05-08), S.4801-4814 |
| Datensatznummer |
250018641
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| Publikation (Nr.) |
 copernicus.org/acp-13-4801-2013.pdf |
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| Zusammenfassung |
Size-resolved trace metal concentrations of 15 elements in aerosol particles
at the Cape Verde Atmospheric Observatory (CVAO) under remote background
conditions were investigated through analysis of aerosol samples collected
during intensive field studies from January 2007 to November 2011 using
total reflection x-ray fluorescence (TXRF). The identification of the main
air mass origin that influence remote marine aerosol in the northern
tropical Atlantic has been investigated. In total, 317 samples were
collected. The dataset was analyzed according to the main air mass inflow at
the station. We found that remote conditions make up about 45% of the
meteorological conditions in a year at CVAO and thus the northern tropical
Atlantic. Surprisingly, air masses from North America are often responsible
for higher trace metal concentrations in this region.
Elements such as Zn, Pb, Cu, Cr, Ni, and V were mostly found in the
submicron size fractions, while elements with dominant crustal or oceanic
origin such as Fe, Ti, Mn, Sr, and Rb were found in the coarse fractions
(>1 μm). The highest metal concentrations, especially for
Zn (3.23 ng m−3), Cu (0.81 ng m−3), Sr
(2.63 ng m−3), and Cr (0.53 ng m−3), were
observed in air masses originating from North America and the concentrations
were within the same concentration range to those reported previously in the
literature for remote marine aerosols. Fe (12.26 ng m−3),
Ti (0.91 ng m−3), and Mn (0.35 ng m−3)
showed higher concentrations when air mass came from Europe and the Canary
Islands. Pb concentration was low (<0.20 ng m−3)
and did not vary significantly with air mass direction. The low Pb
concentration is indicative of the complete phase-out of leaded gasoline
even in African countries. Crustal enrichment factor values decreased from
fine to coarse-mode particles with low values (<4) observed for Fe,
Mn, and Rb, and high values (>20) for Zn, Cu, Ni, Cr, Pb, and Se.
The observed enrichment of the elements was attributed to crustal, marine,
anthropogenic, and biogenic sources, as well as long-range transport and
resuspension. Zn, Cu and Pb were indicators of anthropogenic activities,
while Ti and Sr were indicators of crustal and marine origin,
respectively. Oceanic and biogenic emissions might have contributed to most
of the Se observed. This work provides the first long-term size-resolved
trace metals study for remote tropical northern Atlantic marine aerosols and
the dataset could serve as good initiation of yearly flux estimates. |
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