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| Registros recuperados: 32 | |
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| Panutrakul, S.; Baeyens, W.F.J.. |
| The Ballasplaat intertidal mud flat in the Scheldt estuary has been polluted by Cd and Pb and also high amounts of organic matter as a result of suspended matter deposition. The degree of pollution is, however, not uniform over the mud flat due to varying physico-chemical conditions (essentially variable redox profiles). Measurements of the redox profile, and the metal concentrations in the pore water, the total sediment and the fraction <63 µm combined with sequential extraction results and enrichment factors can explain the behaviour of Cd, Pb, Fe and Mn in the sediments. In a strong anoxic sediment, where sulphate reducing bacteria are active, the heavy metals are trapped as poorly soluble metal complexes while in an oxic or suboxic sediment metals... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Cadmium Chemical reactions Estuaries Iron Lead Manganese Marine pollution Mud flats Physicochemical properties Sediment chemistry Sediment pollution Sediments ANE; Netherlands; Westerschelde; Ballastplaat. |
| Ano: 1991 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3112 |
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| Dauby, P.; Baeyens, W.F.J.; Biondo, R.; Bouquegneau, J.-M.; Chou, L.; Collette, O.; Dehairs, F.A.; Elskens, M.; Frankignoulle, M.; Loijens, M.; Paucot, H.; Wollast, R.. |
| From 1989 to 1992, five cruises were conducted in an area covering the English Channel, the Celtic Sea and the Gulf of Biscay. During these campaigns, suspended matter was collected by different techniques in order to analyze the spatial and vertical distribution of several particulate trace elements in relation to the global biogeochemical cycle of carbon. It appears that horizontal distribution varies strongly from one element to another and is mainly influenced either by anthropogenic and terrigenous inputs or by scavenging processes. On the other hand, the vertical distribution seems mainly linked to the primary production. In parallel to these trace element measurements, experiments were carried out to estimate the transfer rates of these elements... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1993 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=2680 |
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| Baeyens, W.F.J.; Goeyens, L.; Monteny, F.; Elskens, I.. |
| Samples from the Scheldt estuary have been assayed for dissolved Cd, Cu and Zn using differential pulse anodic stripping voltammetry, either as total (after UV irradiation) or labile concentrations. Under these experimental conditions, labile concentrations ranged between 51-65% of total Cu, 16-66% of total Zn and 53-91 % of total Cd. The metal-organic interactions were assessed by evaluating (a) the distribution coefficient K<sub>d</sub> for the distribution of the metals between the liquid phase (complexation) and their binding to particulate matter, and (b) the competitive effect exerted by inorganic complexing ligands using a multi-element interaction model. The proportion of organically bound metals (strong and labile) was estimated, in... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7051 |
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| Dehairs, F.A.; Dedeurwaerder, H.; Dejonghe, M.; Decadt, G.; Gillain, G.; Baeyens, W.F.J.; Elskens, I.. |
| During 1980 and 1981 the aerosol burden as well as the wet and dry atmospheric fall-out of Cu, Cd, Pb, Zn, Fe and Mn to the sea have been studied in the Belgian coastal area. Atmospheric Cu, Zn and Cd are observed to be introduced into the sea mainly by wet fall-out, while Fe, Mn and also Pb have a dry and wet fall-out of similar magnitude. Of these elements, Cu, Zn and Cd have the highest washout factors. Furthermore, for all elements, excepted Mn, discrepancies exist between washout factors above land and sea, with values up to 5 times larger above the sea.On the scale of the North Sea, atmospheric fall-out of Cu, Zn, Pb and Cd exceeds by one order of magnitude the combined input of the rivers Scheldt, Rhine and Meuse, while fall-out of Fe and Mn is of... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1982 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=10065 |
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| Baeyens, W.F.J.; Van Eck, B.T.M.; Lambert, C.; Wollast, R.; Goeyens, L.. |
| A general description of the Scheldt estuary, including the hydrology, the sediment transport, the productivity and the biodegradation with respect to their influence on the trace metal behaviour in the Scheldt estuary, is given. The river basin can be divided in several sections according to their morphological, hydrodynamical and sedimentary properties. The zone from km 78 to 55, which corresponds roughly with the salinity zone from 2 to 10 psu, is the zone of high turbidity, high sedimentation and of oxygen depletion, especially in the summer period. That area is called the geochemical filter because the solid/dissolved distribution of the trace metals is controlled by redox, adsorption/desorption, complexation and precipitation/coprecipitation... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: ANE; Netherlands; Westerschelde. |
| Ano: 1998 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7040 |
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| Goeyens, L.G.; Stichelbaut, L.W.; Post, E.J.; Baeyens, W.F.J.. |
| A new procedure for the conversion of bound nitrogen into nitrogen gas, applicable to solid material, is described. It embodies two main stages: the catalytic ammonification of the sample and the consecutive transformation of ammonium to molecular nitrogen by the modified Dumas method. The first step of the preparation is carried out in a quartz reactor, filled with granular nickel, at a temperature of 700°C, the ammonia gas produced being trapped in sulphuric acid. In the second step, this solution is neutralised, dried and subjected to the Dumas combustion.The addition of reagents does not influence the results of the measurements. Spectrometric <sup>15</sup>N percentage abundances are converted into mass spectrometric "true"... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Emission spectroscopy. |
| Ano: 1985 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3279 |
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| Baeyens, W.F.J.; Elskens, M.; Gillain, G.; Goeyens, L.. |
| Cu, Zn, Cd and Pb have been analysed in suspended matter and water samples from the Scheldt estuary, collected during five cruises between May 1982 and May 1983. In order to evaluate the overall metal behaviour in the estuary, continuous longitudinal profiles of the total, the particulate and the dissolved metal concentrations are discussed in relation to various specific physico-chemical parameters. By means of correlation and multi-regression techniques, several estuarine processes could be identified which dominate and/or control the behaviour of the individual trace metals in three distinct areas of the Scheldt estuary. The behaviour of the four selected metals was found to show some common features, but is besides this also characterised by many... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7043 |
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| Lansens, P.; Baeyens, W.F.J.. |
| An improvement in the extraction step in the method of Decadt et al. for determining methylmercury in biological tissues is described. The methylmercury is released from the tissue by use of sulphuric acid as the cleaving agent and immediately converted to the iodide form by iodoacetic acid. These reaction steps take place in a closed headspace vial. The methylmercury iodide is then headspace-injected into a gas-chromatograph and detected with a microwave-induced plasma detector. Quantitation is accomplished by standard addition. Analysis of one sample takes less than 15 min. The detection limit of the method is 20 ng methylmercury per gram biological tissue when 50 mg of tissue are taken. |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1990 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3091 |
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| Baeyens, W.F.J.; Elskens, I.; Van Ryssen, R.; Leermakers, M.. |
| Offshore fluxes of Cu, Zn, Cd, Pb and Hg were calculated based on residual flow patterns and salinity gradients along the Belgian coast. The residual flow lines along the Belgian coast are more or less parallel to the coast except the area where the north-easterly flowing water mass coming from the Channel encounters the south-westerly-oriented Scheldt outflow, forming a residual hydrodynamical front. From the steady-state salinity pattern, diffusion coefficients perpendicular to the residual flow were deduced; they ranged from 21 to 108 m² s-¹ . Offshore fluxes of dissolved and particulate trace metals based on diffusive and mixing processes are calculated. The steady state profiles of dissolved metals show a dilution effect in the coastal waters,... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7055 |
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| Baeyens, W.F.J.; Parmentier, K.; Goeyens, L.; Ducastel, G.; De Gieter, M.; Leermakers, M.. |
| Cd, Cu, Zn and Pb concentrations in both dissolved and particulate phase were assessed during 1995. Data Quality Assurance was an integral part of this study and involved all major steps of the analysis procedure such as sampling, sample handling, preconcentration and determination. Desorption and redox processes clearly control the dissolved Cu and Cd profiles. Mobilisation of dissolved Zn is small and essentially restricted to the low salinity area and the late spring survey. Dissolved Pb shows the clearest dilution pattern. The parameters representative of these processes (dissolved oxygen and salinity) also correlate very well with the particulate metal profiles. In addition, the plankton activity (expressed by the chlorophyll-<i>a</i>... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7046 |
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| Baeyens, W.F.J.; Leermakers, M.; Molina, R.; Holsbeek, L.; Joiris, C.R.. |
| Aqueous distillation is a common initial step in the determination of monomethyl mercury (MMHg) in a variety of matrices. However, recently it was observed that during distillation, MMHg may be generated from inorganic mercury and induce in some cases significant analytical errors. Therefore we investigated a number of alternative analytical techniques for the determination of MMHg in sediments and biological tissues: (1) headspace-GC-AFS and some variants; (2) acid extraction-solvent extraction-GC-AFS; (3) acid extraction-solvent extraction-GC-ECD. Methods (2) and (3) showed MMHg generation when an inorganic Hg spike was added to the sediment sample. The headspace method yielded MMHg results in agreement with the reference values for biological and... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1999 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=6829 |
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| Baeyens, W.F.J.; Monteny, F.; Van Ryssen, R.; Leermakers, M.. |
| The behaviour of Cu, Zn, Cd, and Pb in the Scheldt estuary was investigated in the periods 1981 to 1993 and 1995. The Hg behaviour was studied between 1992 and 1994. A box model was used to establish the relationship between the trace metal inputs and the fate of these pollutants in the Scheldt estuary. Annual budgets were calculated for particulate and dissolved trace metals. For Hg, seasonal budgets of the various species (inorganic Hg, methylmercury, Hg°) could also be calculated. These budgets allow an evaluation of the consistency of each individual flux or process, such as the inputs of the various metals into the North Sea, the sedimentation flux of particulate metals in the area of high turbidity, the evasional fluxes and the formation rates of... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7059 |
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| Registros recuperados: 32 | |
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