Consulta: creatorFacets:"Leermakers, M."
Registros recuperados: 6
Data/hora: 08/06/2024 11:59:54

The impact of the Scheldt input on the trace metal distribution in the Belgian coastal area (results of 1981-1983 and 1995-1996)
Provedor de dados: 27
Autores: 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
Ano: 1998
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7055

The biogeochemical behaviour of Cd, Cu, Pb and Zn in the Scheldt estuary: results of the 1995 surveys
Provedor de dados: 27
Autores: 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-&lt;i&gt;a&lt;/i&gt;...
Tipo: Info:eu-repo/semantics/article
Ano: 1998
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7046

Determination of methylmercury in natural waters by headspace gas chromatography with microwave-induced plasma detection after preconcentration on a resin containing dithiocarbamate groups
Provedor de dados: 27
Autores: Lansens, P.; Meuleman, C.; Leermakers, M.; Baeyens, W.F.J.
A method for the determination of methylmercury at ng 1&lt;sup&gt;-1&lt;/sup&gt; levels in natural waters is described. Methylmercury present in a sample is first preconcentrated on a column of a resin containing dithiocarbamate groups and eluted quantitatively with acidic thiourea solution. Methylmercury in the effluent is then converted to the iodide by addition of sulphuric acid and iodoacetic acid and determined by headspace gas chromatography with microwave-induced plasma detection. The adsorption properties of the resin are discussed.
Tipo: Info:eu-repo/semantics/article
Ano: 1990
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3092

Investigation of headspace and solvent extraction methods for the determination of dimethyl- and monomethylmercury in environmental matrices
Provedor de dados: 27
Autores: 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
Ano: 1999
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=6829

A box-model of metal flows through the Scheldt estuary (1981-1983 and 1992-1995)
Provedor de dados: 27
Autores: 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
Ano: 1998
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7059

Behaviour and speciation of mercury in the Scheldt estuary (water sediments and benthic organisms)
Provedor de dados: 27
Autores: Baeyens, W.F.J.; Meuleman, C.; Muhaya, B.; Leermakers, M.
Surface waters, sediments and the polychaete &lt;i&gt;Nereis diversicolor&lt;/i&gt; were sampled in the Scheldt Estuary between 1990 and 1994. In surface waters particulate Hg (Hg&lt;sub&gt;p&lt;/sub&gt;) concentrations ranged from 350-1610 ng g-¹. They are essentially controlled by physical mixing of polluted fluvial particulates with relatively unpolluted marine particulates, but unaffected by seasonal changes. Dissolved Hg species, on the other hand, show large seasonal variations essentially controlled by the redox conditions in the estuary, as well as by bacterial and phytoplankton activity. Total dissolved (Hg&lt;sub&gt;TD&lt;/sub&gt;) concentrations ranged from 0.5 to 3.0 ng l-¹ with 10 to 90% as reactive Hg. High concentrations of...
Tipo: Info:eu-repo/semantics/article
Ano: 1998
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7047