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See detailResponse of primary production and calcification to changes of pCO(2) during experimental blooms of the coccolithophorid Emiliania huxleyi
Delille, Bruno ULg; Harlay, Jérôme ULg; Zondervan, Ingrid et al

in Global Biogeochemical Cycles (2005), 19(2),

[1] Primary production and calcification in response to different partial pressures of CO2 (PCO2) ("glacial,'' "present,'' and "year 2100'' atmospheric CO2 concentrations) were investigated during a ... [more ▼]

[1] Primary production and calcification in response to different partial pressures of CO2 (PCO2) ("glacial,'' "present,'' and "year 2100'' atmospheric CO2 concentrations) were investigated during a mesocosm bloom dominated by the coccolithophorid Emiliania huxleyi. The day-to-day dynamics of net community production (NCP) and net community calcification (NCC) were assessed during the bloom development and decline by monitoring dissolved inorganic carbon (DIC) and total alkalinity ( TA), together with oxygen production and 14 C incorporation. When comparing year 2100 with glacial PCO2 conditions we observed: ( 1) no conspicuous change of net community productivity (NCPy); ( 2) a delay in the onset of calcification by 24 to 48 hours, reducing the duration of the calcifying phase in the course of the bloom; ( 3) a 40% decrease of NCC; and ( 4) enhanced loss of organic carbon from the water column. These results suggest a shift in the ratio of organic carbon to calcium carbonate production and vertical flux with rising atmospheric PCO2. [less ▲]

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See detailGeochemical composition of sediments in the Scheldt
Bouezmarni, Mohamed ULg; Wollast, Roland

in Hydrobiologia (2005), 540(1-3), 155-168

Superficial sediments of the Scheldt estuary were collected with a Van Veen grab at 57 stations between Temse and Vlissingen. They were analysed for major elements (Si, Al, Fe, Ca, Mg, Na, K, Cinorg and ... [more ▼]

Superficial sediments of the Scheldt estuary were collected with a Van Veen grab at 57 stations between Temse and Vlissingen. They were analysed for major elements (Si, Al, Fe, Ca, Mg, Na, K, Cinorg and Corg) and trace metals (Cd, Pb, Cu, Zn, Cr, Ni, Co, Mn and Li). Factor analysis indicates that 44% of the variance can be explained by one factor which exhibits a high saturation for trace metals, organic matter, Al and Fe, all variables typical of fine mud. The high scores of this first factor are almost exclusively present in the upper estuary except for one area in front of Terneuzen. The second factor, which explains 23% of the variance, is typical of the carbonates and the third one (19% of the variance) is representative of the clay minerals. These two factors are more evenly distributed over the estuary. As usual, a strong influence of granulometry on the distribution of trace elements in the sediments was observed. Intercomparison of their composition within the Scheldt or with those of other aquatic systems requires thus a normalization procedure. This problem has been studied in detail by analysing various size fractions (63–16, 16–8, 8–4, <4 m) obtained by elutriation of the sample or by using a parameter characteristic of the fine fraction such as the concentration of a typical element (Al, Fe, Li, Corg). The normalization of trace metals allowed us to evaluate an enrichment factor of the trace elements in the estuarine deposits due to mans activities. In addition, it demonstrates the decrease of the anthropogenic impact on the composition of sediments by comparing the composition of sediments collected in 1976 and in 1994. [less ▲]

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See detailDelayed and reduced coccolithophorid calcification under elevated PCO2
Delille, Bruno ULg; Harlay, Jérôme ULg; Zondervan, Ingrid et al

Poster (2004, May 10)

Numerous experiments to date have demonstrated that elevated PCO2 is detrimental to biogenic calcification rates. However, most of these experiments have been realized in batch or continuous cultures and ... [more ▼]

Numerous experiments to date have demonstrated that elevated PCO2 is detrimental to biogenic calcification rates. However, most of these experiments have been realized in batch or continuous cultures and give little information on the dynamics of calcification in natural conditions. The present work describes the development and decay of a nutrient-induced bloom of the coccolithophorid Emiliania huxleyi in a mesocosm experiment. The monitoring of Dissolved Inorganic Carbon (DIC) and Total Alkalinity (TAlk) within the seawater enclosures allowed us to describe comprehensively day to day dynamics of both calcification and organic carbon production. Three atmospheric PCO2 conditions (glacial, present and next century) were simulated by bubbling CO2 mixtures, while total alkalinity was left to evolve from its present value. No conspicuous change of Net Community Production under elevated PCO2 was recorded while the production of inorganic carbon appeared to be affected in two ways. Firstly, the production rate of inorganic carbon appeared to be lowered by 40% in the next century PCO2 conditions, decreasing concomitantly the calcification to photosynthesis ratio from 0.75 (glacial conditions) to 0.45 (next century conditions). Secondly, the onset of calcification was delayed by 24~48h under elevated PCO2 conditions, reducing the overall length of calcification in the course of the bloom. These two effects would act to reduce the amount of precipitated CaCO3 by coccolithophorids in a High CO2 world [less ▲]

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See detailOn the coupling of primary production and calcification at the continental margin
Harlay, Jérôme ULg; Chou, Lei; Roevros, Nathalie et al

Poster (2004, March 05)

Until now, little attention has been paid to the processes controlling the production, dissolution and fate of biogenic calcium carbonate in the oceans. It is however well known that net deposition rates ... [more ▼]

Until now, little attention has been paid to the processes controlling the production, dissolution and fate of biogenic calcium carbonate in the oceans. It is however well known that net deposition rates of inorganic carbon to the sediments are comparable to those of organic matter. There remains still large uncertainties concerning the production and redissolution of biogenic carbonate in the marine system and thus about the role of the carbonate pump in response to anthropogenic CO2 perturbations. The understanding of these processes is also a prerequisite to predict the response of marine organisms to global environmental changes. In the framework of the Belgian global change programme, we have developed a project devoted to the study of the inorganic carbon cycle in the Bay of Biscay where coccolithophorid blooms occur frequently. The study focuses on processes associated with the oceanic production and dissolution of calcium carbonate, by combining field investigations, laboratory experiments and modelling efforts. Remote sensing demonstrates a close relationship between vertical mixing along the continental margin and the development of the phytoplankton bloom. We will present here, results of 14C incorporation experiments used to evaluate the rate of production of organic and inorganic particulate carbon, obtained during a coccolithophorid spring bloom in the investigated area. A tentative mass balance of the carbon fluxes for this area will be presented, confirming the importance that the calcium carbonate pump may play in the oceanic system. [less ▲]

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See detailOn the coupling of primary production and calcification during a field experiment in the northeastern Atlantic
Chou, Lei; Harlay, Jérôme ULg; Roevros, Nathalie et al

Poster (2003, April 06)

The role of calcifying phytoplanktonic organisms in ocean carbon biogeochemistry and in climate change has received increasing attention in the marine community. The quantification of the production of ... [more ▼]

The role of calcifying phytoplanktonic organisms in ocean carbon biogeochemistry and in climate change has received increasing attention in the marine community. The quantification of the production of biogenic calcium carbonate and associated organic matter in the photic zone and of their fate during settling is essential for a better assessment of the oceanic carbon cycle. In the framework of the Belgian global change programme, we conducted a field experiment on board the R/V Belgica in Spring 2002 along the Northern Bay of Biscay margin during successive coccolithophorid Emiliania huxleyi (Ehux) blooms. We aim, in particular, at quantifying the role of calcifying phytoplanktonic organisms in sequestering carbon. With near real-time transmission of remote sensing data during the survey, we were able to track the position and evolution of the various coccolithophore blooms along the shelf break. Bio-optical measurements were performed for modelling purpose and for calibration of the recently launched MERIS Sensor. During the field campaign, special attention was paid to the precise determination of the dissolved inorganic carbon chemistry. Primary production and rate of calcification were measured using C14 incorporation experiments and the organic to inorganic particulate carbon ratio quantified. Phytoplankton speciation was determined by microscopic examination, flow cytometry and HPLC pigment analyses. Zooplankton grazing experiments on phytoplankton were also performed. Suspended particles were characterised by their chemical composition and morphology. Th234 was used to quantify particle residence times and particulate organic carbon fluxes in surface waters. The results indicate significant particle export during the sampling period, with particle residence times in the upper 80 m ranging from 15 to 45 days. In this presentation, we will integrate the results obtained from remote sensing, biooptical investigation, water chemistry and process studies to elucidate the coupling of primary production and calcification during Ehux blooms and its importance in the marine biogeochemical cycle of carbon. [less ▲]

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See detailQuantification of the Carbonate Pump: Case study of an Emiliania huxleyi bloom in the Bay of Biscay
Harlay, Jérôme ULg; Chou, Lei; Roevros, Nathalie et al

Poster (2003, April 03)

Little attention has been paid until now to the processes controlling the production, dissolution and fate of biogenic calcium carbonate in the oceans. It is however well known that net deposition rates ... [more ▼]

Little attention has been paid until now to the processes controlling the production, dissolution and fate of biogenic calcium carbonate in the oceans. It is however well known that net deposition rates of inorganic carbon to the sediments are comparable to those of organic matter. There remains still large uncertainties in the production and redissolution of biogenic carbonate in the marine system and thus about the role of the carbonate pump in response to anthropogenic CO2 perturbations. The understanding of these processes is also a prerequisite to predict the response of marine organisms to global environmental changes. In the framework of the Belgian global change programme, we have developed a project devoted to the study of the inorganic carbon cycle in the Bay of Biscay where coccolithophorid blooms occur frequently. The study focuses on processes associated with the oceanic production and dissolution of calcium carbonate, by combining field investigations, laboratory experiments and modelling efforts. Remote sensing demonstrates a close relationship between vertical mixing along the continental margin and the development of the phytoplankton bloom. We will present here, results of 14C incorporation experiments used to evaluate the rate of production of organic and inorganic particulate carbon, obtained during a coccolithophorid spring bloom in the investigated area. A tentative mass balance of the carbon fluxes for this area will be presented, confirming the importance that the calcium carbonate pump may play in the oceanic system. [less ▲]

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See detailAssessment of the importance of the carbonate pump in surface waters of the Bay of Biscay
Harlay, Jérôme ULg; Chou, Lei; Dedonder, Virginie et al

Poster (2003, January 07)

Marine carbon research in the past decade has been mainly devoted to the understanding and quantification of processes controlling the fluxes of organic matter in the ocean. Little attention has been paid ... [more ▼]

Marine carbon research in the past decade has been mainly devoted to the understanding and quantification of processes controlling the fluxes of organic matter in the ocean. Little attention has been paid until now to the particulate inorganic carbon whose net fluxes to the sediments are comparable to those of the organic matter. There remains still a large uncertainty in the production and the fate of biogenic calcium carbonate in the oceanic carbon cycle. In the framework of the Belgian global change programme, we have developed a project devoted to the study of the inorganic carbon cycle in the Bay of Biscay where coccolithophorid blooms occur frequently. The study focuses on processes associated with the oceanic production and dissolution of calcium carbonate, by combining field investigations, laboratory experiments and modelling efforts. The rate of primary production and of calcification by phytoplankton is evaluated by 14C incubation experiments during a coccolithophorid bloom-forming period in the area of investigation. The relative production of organic matter and calcium carbonate in the photic zone along a transect from the continental shelf across the slope to deep waters will be presented. A tentative mass balance of the carbon fluxes for this area will be constructed. These preliminary results confirm the importance that the calcium carbonate pump may play in open ocean. [less ▲]

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See detailCalcification and organic production of coccolithophorids Emiliania huxleyi under different atmospheric pCO2 in a mesocosm experiment
Delille, Bruno ULg; Harlay, Jérôme ULg; Chou, Lei et al

Poster (2003, January 07)

The response of primary production and calcification of the coccolithophorid Emiliania huxleyi to different partial pressures of CO2 (p CO2) have been investigated during a mesocosm bloom experiment in a ... [more ▼]

The response of primary production and calcification of the coccolithophorid Emiliania huxleyi to different partial pressures of CO2 (p CO2) have been investigated during a mesocosm bloom experiment in a Norwegian fjord. Glacial, present and next century atmospheric p CO2 conditions (respectively 180, 370 and 700 ppmV) have been simulated above the surface of large sea-water enclosures. If production of organic matter remains constant under elevated p CO2, the production of inorganic carbon appears to be affected in two ways. First, the beginning of calcification is delayed. Second, the production rate of inorganic carbon appears to be lowered by 40% in the future conditions, decreasing subsequently the calcification/photosynthesis ratio from 1 to 0.6. During the experiment a strong viral growth have been experienced, which have seriously depressed calcification as well. We propose the threshold of 5.10 6 cell/ml for E huxleyi virus abundance above which the production and calcification of the population of E. huxleyi are severely affected. [less ▲]

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See detailAPPLICATION DU MODELE PEGASE AU BASSIN RHIN-MEUSE (France)
Smitz, Joseph ULg; Everbecq, Etienne ULg; Deliège, Jean-François ULg et al

in Garnier, Josette; Mouchel, Jean-Marie (Eds.) Man and river systems: the functioning of river systems at the basin scale (2000)

Le modèle PEGASE (Planification Et Gestion de l’ASsainissement des Eaux) a été développé afin d'orienter les choix en matière de gestion des eaux de surface par le calcul prévisionnel et déterministe de ... [more ▼]

Le modèle PEGASE (Planification Et Gestion de l’ASsainissement des Eaux) a été développé afin d'orienter les choix en matière de gestion des eaux de surface par le calcul prévisionnel et déterministe de la qualité des eaux en fonction des apports et rejets polluants, dans des conditions hydrologiques diverses. A la demande de l'Agence de l'Eau Rhin-Meuse, une application de PEGASE a été menée sur le bassin Rhin-Meuse de manière à fournir à l'Agence un outil de gestion de la qualité des eaux de surface et un outil de planification de l'épuration des eaux usées. Dans le cas de l'application de PEGASE au bassin Rhin-Meuse, des simulations générales ont été effectuées pour l'ensemble du bassin (36.000 km², 185 rivières). Ensuite, des sous-bassins particuliers (la Bruche et la Moder) ont été étudiés de manière plus approfondie. Ces simulations ont permis de comparer différents scénarios d'épuration. [less ▲]

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See detailPEGASE, une méthodologie et un outil de simulation prévisionnelle pour la gestion de la qualité des eaux de surface
Smitz, Joseph ULg; Everbecq, Etienne ULg; Deliège, Jean-François ULg et al

in Tribune de l'Eau (La) (1997), 50/4(588), 73-82

PEGASE (Planification Et Gestion de l’ASsainissement des Eaux) est un modèle intégré bassins hydrographiques/rivières développé à l’Aquapôle qui permet de calculer de façon déterministe et prévisionnelle ... [more ▼]

PEGASE (Planification Et Gestion de l’ASsainissement des Eaux) est un modèle intégré bassins hydrographiques/rivières développé à l’Aquapôle qui permet de calculer de façon déterministe et prévisionnelle la qualité des eaux des rivières en fonction des rejets et apports de pollution. PEGASE est un outil opérationnel permettant d’orienter les choix des opérateurs publics et privés en matière de gestion des eaux de surface à l’échelle des bassins versants [less ▲]

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See detailBiogeochemical Studies conducted in the OMEX Area during the BELGICA cruises: Preliminary Results
Chou, Lei; Loijens, Michèle; Paucot, Hugues et al

Poster (1994, October)

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See detailExchanges at the Ocean Margins.
Wollast, Roland; Elskens, Marc; Dauby, Patrick ULg et al

Conference (1993, January)

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See detailDistribution of particulate trace elements in the Northeastern Atlantic
Dauby, Patrick ULg; Baeyens, Willy; Biondo, Renzo ULg et al

in Progress in Belgian Oceanographic Research (1993)

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See detailPEGASE, Planification et gestion de l'assainissement des eaux de surface
Smitz, Joseph ULg; Everbecq, Etienne ULg; Lorea, Bernard et al

Report (1991)

PEGASE (Planification Et Gestion de l’ASsainissement des Eaux) est un modèle intégré bassins hydrographiques/rivières qui permet de calculer de façon déterministe et prévisionnelle la qualité des eaux des ... [more ▼]

PEGASE (Planification Et Gestion de l’ASsainissement des Eaux) est un modèle intégré bassins hydrographiques/rivières qui permet de calculer de façon déterministe et prévisionnelle la qualité des eaux des rivières en fonction des rejets et apports de pollution (relation pression-impact). Ce rapport de synthèse reprend la description du travail réalisé pendant 3 ans, et qui a permis de construire la première version du modèle, appliquée sur le territoire de la Région Wallonne. [less ▲]

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See detailThe influence of acid rains on the geochemistry of aluminium
Wollast, Roland; Chou, L.; Debbaut, Vincent ULg et al

in Scope Belgium : proceedings : acid deposition and sulphur cycle (1984, June)

Detailed reference viewed: 11 (1 ULg)