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| Registros recuperados: 50 | |
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| Struyf, H.; Van Grieken, R.. |
| An overview of the wet deposition of micropollutants (trace metals -Cd, Cr, Cu, Pb, Hg, Zn- and organic compounds -PAHs, PCBs, pesticides) to the North Sea and adjacent areas is presented. The results of (in)direct measurements of the wet flux are compared to modeling results. Attention is given to specific problems like revolatilization, sea-spray, contamination, gas-to-particle ratios in wet deposition of Hg and the organic substances. Also, the importance of wet deposition is weighted to that of dry deposition and non-atmospheric input routes to the North Sea. It is concluded that -especially for organic micropollutants- current knowledge is insufficient to yield an accurate and detailed image of the impact and importance of wet deposition to the North... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1993 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=2785 |
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| Chakravorty, R.; Van Grieken, R.. |
| The coprecipitation of Cd, Co and Eu from seawater onto ferric hydroxide was studied, using the radioactive tracers <sup>109</sup>Cd, <sup>60</sup>Co and <sup>152-154</sup>Eu, as a function of the pH, the concentration of the collector iron, the concentration of the metal spike and the aging of the internally formed precipitate. For preconcentration purpose, a pH 9 and a 35 ppm iron concentration appeared to be suitable. At pH 8, the natural pH of seawater, the distribution coefficients for Cd, Co and Eu are 10<sup>4.5</sup>, 10<sup>5</sup> and 10<sup>7</sup>, respectively. |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Cadmium; Coprecipitation; Radiochemistry; Sea water. |
| Ano: 1986 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3236 |
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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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| Hoornaert, S.; Van Malderen, H.; Van Grieken, R.. |
| Ca-containing particles, especially CaSO<sub>4</sub> particles, have been encountered in several atmospheric aerosol studies. An overview is given of the different sources of airborne Ca-containing particles. The North Sea atmosphere is studied to identify the different Ca-containing particle types and to find the correlation between their occurrence and the source regions of the corresponding air masses. About 50,000 individual aerosol samples were collected above the Southern Bight of the North Sea for several wind directions and analyzed for their composition using electron probe X-ray microanalysis. Nonhierarchical cluster analysis is performed on the data to reveal the differentparticle types, their relative abundances and their sources.... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Aerosols; Calcium. |
| Ano: 1996 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=2974 |
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| Scholkovitz, E.R.; Van Grieken, R.; Eisma, D.. |
| A study of the major-element (Si, Al, Fe, K, Mg, Ca, Ti, Mn and P) composition of suspended matter in the surface waters of the Zaire River and Estuary revealed that this material was enriched in Al, Fe and P and depleted in Si, Ca, K and Mg relative to recent pelagic sediments and to suspended matter carried by the Amazon River. These enrichments and depletions are characteristic of soils in regions of intense chemical weathering as is the situation in western equatorial Africa. Suspended samples from waters near the bottom of the estuary have compositions which indicate that this material has undergone much less chemical weathering. These particles were of greater size and most likely contained a larger proportion of quartz, micas, feldspars and oxides... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Suspended inorganic matter Africa; Zaire R.. |
| Ano: 1978 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3619 |
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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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| Brügmann, L.; Bernard, P.C.; Van Grieken, R.. |
| In 1984, on a transect covering the whole Baltic Sea and parts of the adjacent North Sea, 160 water samples were taken and analysed for their concentrations of particulate and dissolved metals. In addition, the suspended materials were investigated for their elemental bulk composition.The particulate fractions represented from about 5% (Cd, Cu and Ni) to 50% (Fe and Pb) of the total (particulate plus dissolved) concentrations. For some elements (Ba, Cd, Cu, Pb and Zn), the particulate matter from the surface microlayer was enriched with respect to those suspended materials taken from 0.2 m depth. This could reflect the atmospheric input of metal-rich aerosols. In anoxic deep waters, maximum contents of Zn (6400 µg g <sup>-1</sup>), Cu (1330 µg... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1992 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=2695 |
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| Martin, J.-M.; Thomas, A.J.; Van Grieken, R.. |
| The results of a preliminary study of trace element concentrations in the Zaire River and estuary suspended sediments are presented. Zaire River concentrations show a close agreement with those observed in other rivers of the world (including Magdalena and Parana). Within the mixing zone, lanthanides, Th, Sc, Hf and Rb remain nearly constant, whereas Cr, Co, Ni, Cu, Zn and Pb concentrations show much more scattering and are either constant or increasing. This last distributions differ significantly from the results of studies conducted in partially mixed estuaries. |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Suspended sediments Trace elements Africa; Zaire R.. |
| Ano: 1978 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3620 |
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| Ro, C.-U.; Osán, J.; Van Grieken, R.. |
| The determination of low-Z elements such as carbon, nitrogen, and oxygen in atmospheric aerosol particles is of interest in studying environmental pollution. Conventional electron probe microanalysis technique has a limitation for the determination of the low-Z elements, mainly because the Be window in an energy-dispersive X-ray (EDX) detector hinders the detection of characteristic X-rays from light elements. The feasibility of low-Z element determination in individual particles using a windowless EDX detector is investigated. To develop a method capable of identifying chemical species of individual particles, both the matrix and the geometric effects of particles have to be evaluated. X-rays of low-Z elements generated by an electron beam are so soft... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1999 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=4028 |
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| Otten, P.; Injuk, J.; Rojas, C.; Van Grieken, R.. |
| The North Sea is being under loaded in many ways, both by organic and anorganic pollutants. Transport over rivers is the most evident way. Direct emission along the coastline and dumping of toxic materials by vessels are another two causes of pollution. Exploitation of oil and gas platforms also lead to operational emission of certain noxious substances. “Last but not least” a part of the pollutants also reach the North Sea through the atmosphere.This article specifically concerns the latter facet of North Sea Pollution. Both gaseous and particular material is being emitted in the atmosphere through incineration and other polluting processes. After physical dispersion and chemical transformation, these pollutants can end up in the sea through deposit... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1992 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=2850 |
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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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| Van Malderen, H.; Rojas, C.; Van Grieken, R.. |
| In order to investigate the importance of giant airborne particles, air sampling was carried out using an aircraft which flew at different altitudes over the Southern Bight of the North Sea. A set of 25 samples was collected with a steel rod on top of the airplane. Some 12,500 individual particles were analyzed using electron probe X-ray microanalysis. Principal factor analysis allowed identification of four sources of giant aerosol particles: aluminosilicates, combustion processes, industrial processes, and marine sources. Hierarchical and nonhierarchical cluster analysis enabled us to classify the analyzed particles. A clear distinction was found between flights for which the associated air masses were marine or continental. The experimentally found size... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1992 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=2887 |
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| Bruynseels, F.; Storms, H.; Van Grieken, R.; Van der Auwera, L.. |
| On aerosol and rain water samples, collected in the Southern Bight of the North Sea, single particle analyses were performed using both laser microprobe mass analysis and electron-probe X-ray microanalysis in combination with an automated image analysis system.In the aerosols collected from an air mass that had traveled from the Atlantic Ocean along the coast of North France, pure seasalt constituted the most abundant particle type, while aluminosilicates (mostly spherical fly-ash particles) amounted to about 20% and mixed seasalt/aluminosilicates, carbonaceous particles, CaSO<sub>4</sub> and spherical iron oxides contributed each 5-10%. In air masses that had a longer residence time over the continent, spherical iron oxides, carbonaceous... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Aerosols; Rain. |
| Ano: 1988 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3125 |
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| Stroobants, N.; Dehairs, F.A.; Goeyens, L.; Vanderheijden, N.; Van Grieken, R.. |
| The intensity of past biological activity can be correlated with the occurrence of suspended and sedimented barite (BaSO<sub>4</sub>). To date, there is a lack of information on the processes controlling the production of pelagic barite. During the EPOS-2 cruise (November-December 1988), situated in the Scotia Sea-Weddell Sea Confluence, suspended water samples were taken for analysis of total Ba by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and for scanning electron microscopy-electron microprobe (SEM-EMP).The vertical profiles of particulate barium generally show a Ba maximum between 200 and 500 m. SEM-EMP investigation on Scotia-Weddell Sea Confluence profiles provide a possible explanation for the origin of this... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Artemia. |
| Ano: 1992 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=2865 |
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| Registros recuperados: 50 | |
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