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| Rojas, C.M.; Van Grieken, R.; Maenhaut, W.. |
| During the period from September 1988 to October 1989, 23 flights were carried out over the Dutch Continental Shelf of the North Sea and a total of 108 aerosol filter samples were collected. The samples were analyzed for Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br and Pb using both particle-induced X-ray emission (PIXE) and energy-dispersive X-ray fluorescence (EDXRF). The results from PIXE exhibited better precision and lower detection limits than those from EDXRF. Therefore the further discussion and interpretation was based on the PIXE data only. It was observed that Si, S, V, Mn, Ni, Cu and Pb were enriched with respect to the earth's crust. It was seen that winds from the sector Southeast-South contributed most significantly to... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1993 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8422 |
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| Rojas, C.M.; Injuk, J.; Van Grieken, R.E.; Maenhaut, W.. |
| Over a period of eight months, a total of 26 atmospheric particulate matter samples were collected at the location of Tahiti and in other areas of French Polynesia, using a specially equipped sailboat. A 6-stage cascade impact or was used to separate aerosols in the following size classes: > 4,2-4, 1-2,0.5-1,0.25-0.5 and < 0.25 µm equivalent aerodynamic diameter. The resulting set of 156 size segregated aerosol samples was analyzed by particle-induced X-ray emission for 16 elements. This study deals with the concentrations of Na, Mg, Al, Si, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, Br, Sr and Pb. Enrichment factor calculations reveal that Na, Mg, S, A, K, Ca and Sr were little fractionated with respect to bulk sea water, whereas Al, Si, Ti, Mn and Fe... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Aerosols Heavy metals Multivariate analysis Sedimentary environments ISE; French Polynesia. |
| Ano: 2000 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7134 |
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| Rojas, C.M.; Injuk, J.; Van Grieken, R.; Laane, R.W.P.M.. |
| During the period from September 1988 to October 1989, 23 sampling flights were carried out over the Southern Bight of the North Sea. In the campaign, both bulk and size-segregated airborne particulate matter samples were collected. Dry deposition velocities for Cd, Cu, Pb and Zn have been estimated using a modified version of the two-layer of Slinn and Slinn and the particle size distribution obtained from size-fractionated samples. Results pointed out that the main difference between our results and those reported in the literature lies in the aerosol size distribution. Dry deposition rates calculated using these deposition velocities as a function of wind sector showed that continental air masses, particularly those associated with the wind sector west... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1993 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=2745 |
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| Rojas, C.M.; Van Grieken, R.. |
| About 50,000 individual aerosol particles from a total of 108 samples collected at six different altitudes above the Southern Bight of the North Sea. Have been analysed using electron probe-X-ray microanalysis. The results of hierarchical cluster analysis on each sample revealed that, for continental air masses, most of the aerosol particulate matter is characterized by high amounts of aluminosilicates, CaSO<sub>4</sub> and Fe-rich particles. For western and marine air masses there was no change in the composition of the most abundant particle type with height. This is in connection with the rather mixed nature of the atmosphere. Non-hierarchical cluster analysis showed that the most abundant particle types in this airshed are: aluminosilicates... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1992 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=2857 |
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| Rojas, C.M.; Van Grieken, R.; Laane, R.W.P.M.. |
| Dry deposition velocities have been calculated using three different approaches. Turbulent wind profile theory has been used to predict the drag coefficient, wind speed and friction velocity at 10m height when the wind speed is measured at a higher altitude. The resulting parameters were introduced in a two-layer deposition model. The second approach was the well-known model of Slinn and Slinn (1980, Atmospheric Environment 14, 1013-1016), whereas the third corresponded to the model published by Williams (1982, Atmospheric Environment 16, 1933-1938). Results point to clear differences. However, in a field experiment carried out at the Southern Bight of the North Sea, all three approaches show relatively comparable results. The role played by the size... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1993 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=2748 |
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