References of "Borges, Alberto"
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See detailRegional occurence of greenhouses gases in groundwater: Initial results in shallow Belgian aquifers.
Hakoun, Vivien ULg; Gesels, Julie ULg; Tseng, Jean Hsiao-Chun et al

Poster (2015, September)

Currently, the lack of robust, context-distributed subsurface greenhouses gases (GHG) concentrations data is a key bottleneck to reduce the uncertainty range of GHG groundwater input to continental ... [more ▼]

Currently, the lack of robust, context-distributed subsurface greenhouses gases (GHG) concentrations data is a key bottleneck to reduce the uncertainty range of GHG groundwater input to continental surface water bodies such as rivers or lakes estimates. Carbon dioxyde (CO2), methane (CH4) and nitrous oxyde (N2O) are likely to be indirectly transferred to the atmosphere through groundwater discharge into continental surface water bodies. We aim to extend regional-scale estimates of indirect GHG emissions by screening, in numerous hydrogeological (such as alluvial, sandstone, chalk and limestone aquifers) and land use contexts (such as industrial and agricultural), the occurence of these gases. Here, we report and discuss CO2, CH4 and N2O concentrations from an initial survey conducted over selected sites (n= 40) within shallow (0-100 m depth) aquifers in Wallonia (Belgium) for the first time. The preliminary results obtained in this study show that the range of GHG concentrations varies between 5160 and 47544 ppm, 0 and 1064 nmol.L-1, as well as 1 and 5637 nmol.L-1 for the partial pressure of CO2, CH4 and N2O respectively. This new and unique regional dataset provides a first step in developping a refined understanding of favorable contexts for GHG occurence in groundwater which may be used to reduce the uncertainties related to indirect emissions of GHG through groundwater-surface water transfers. [less ▲]

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See detailContribution of cyanobacteria to the building of travertines in a calcareous stream
Wilmotte, Annick ULg; Golubic, Stjepko; Kleinteich, Julia et al

Poster (2015, August 03)

The ambient temperature travertine deposits of the calcareous Hoyoux River (Modave, Belgium) and several tributaries are organized and promoted by the filamentous cyanobacterium identified by its ... [more ▼]

The ambient temperature travertine deposits of the calcareous Hoyoux River (Modave, Belgium) and several tributaries are organized and promoted by the filamentous cyanobacterium identified by its morphotype and ecological properties as Phormidium cf. incrustatum. A combination of techniques was used to study this biotope: physico-chemical parameters and CO2 measurements, Scanning and Transmission Electron Microscopy, RAMAN microspectroscopy. A molecular diversity study with pyrosequencing of the cyanobacterial 16S rRNA is in progress. A potential candidate was isolated in culture. [less ▲]

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See detailGlobally significant greenhouse-gas emissions from African inland waters
Borges, Alberto ULg; Darchambeau, François ULg; Teodoru, Cristian R. et al

in Nature Geoscience (2015), advance online publication

Carbon dioxide emissions to the atmosphere from inland waters[mdash]streams, rivers, lakes and reservoirs[mdash]are nearly equivalent to ocean and land sinks globally. Inland waters can be an important ... [more ▼]

Carbon dioxide emissions to the atmosphere from inland waters[mdash]streams, rivers, lakes and reservoirs[mdash]are nearly equivalent to ocean and land sinks globally. Inland waters can be an important source of methane and nitrous oxide emissions as well, but emissions are poorly quantified, especially in Africa. Here we report dissolved carbon dioxide, methane and nitrous oxide concentrations from 12 rivers in sub-Saharan Africa, including seasonally resolved sampling at 39 sites, acquired between 2006 and 2014. Fluxes were calculated from published gas transfer velocities, and upscaled to the area of all sub-Saharan African rivers using available spatial data sets. Carbon dioxide-equivalent emissions from river channels alone were about 0.4 Pg carbon per year, equivalent to two-thirds of the overall net carbon land sink previously reported for Africa. Including emissions from wetlands of the Congo river increases the total carbon dioxide-equivalent greenhouse-gas emissions to about 0.9 Pg carbon per year, equivalent to about one quarter of the global ocean and terrestrial combined carbon sink. Riverine carbon dioxide and methane emissions increase with wetland extent and upland biomass. We therefore suggest that future changes in wetland and upland cover could strongly affect greenhouse-gas emissions from African inland waters. [less ▲]

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See detailPRESSÃO PARCIAL (PCO2) E FLUXO DE DIÓXIDO DE CARBONO (CO2) EM AMBIENTES DE VÁRZEA AMAZÔNICOS
Amaral, JHF; Barbosa; Kasper, D et al

Conference (2015, July 12)

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See detailMethane distributions and sea-to-air fluxes in the South China Sea and the West Philippines Sea
Tseng; Chen; Borges, Alberto ULg et al

Poster (2015, July 07)

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See detailPhytoplankton abundance and diversity in the Congo river at high and low waters
Stoyneva, MP; Descy, JP; Bouillon, S et al

Conference (2015, July 05)

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See detailLandscape Control on the Spatial and Temporal Variability of Chromophoric Dissolved Organic Matter and Dissolved Organic Carbon in Large African Rivers
Lambert, Thibault ULg; Darchambeau, François ULg; Bouillon, Steven et al

in Ecosystems (2015)

The characteristics of colored dissolved organic matter (CDOM) as well as the concentrations and stable isotope composition (d 13 C) of dissolved organic carbon (DOC) were characterized in several large ... [more ▼]

The characteristics of colored dissolved organic matter (CDOM) as well as the concentrations and stable isotope composition (d 13 C) of dissolved organic carbon (DOC) were characterized in several large rivers of Africa including the Congo, Niger, Zambezi, and Ogooué basins. We compared the spatial and temporal patterns of dissolved organic matter (DOM) quantity and quality along with various environmental gradients, including hydrology, river size, catchment vegetation, and connectivity to land. The optical proxies used include the absorption coefficient at 350 nm, the specific ultraviolet absorbance, and the spectral slope ratio (S R = 275–295-nm slope divided by 350–400-nm slope). Our results show that land cover plays a primary role in controlling both DOC concentration and optical properties of DOM in tropical freshwaters. A higher cover of dense forest in the catchment leads to a higher quantity of highly aromatic DOM in the river network, whereas an increasing savannah cover results in lower DOC concentrations and less absorptive DOM. In addition to land cover, the watershed morphology (expressed by the average slope) exerts a strong control on DOC and CDOM in tropical rivers. Our results also show that the percentage of C3 and C4 vegetation cover is not an accurate predictor for DOM and CDOM quality in rivers due to the importance of the spatial distribution of land cover within the drainage network. The comparison of our results with previously published CDOM data in temperate and high-latitude rivers highlights that DOM in tropical freshwa-ters is generally more aromatic, and shows a higher capacity for absorbing sunlight irradiance. [less ▲]

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See detailVertical Distribution of Functional Potential and Active Microbial Communities in Meromictic Lake Kivu
İnceoğlu, Özgul; Llirós, Marc; Crowe, Sean A. et al

in Microbial Ecology (2015)

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See detailHow phosphorus limitation can control climatic gas emission
Gypens; Borges, Alberto ULg; Speeckaert, Gaëlle ULg et al

Conference (2015, April 12)

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See detailOrganic and inorganic carbon fluxes in a tropical river system (Tana River, Kenya) during contrasting wet seasons
Geeraert, N; Omengo, FO; Bouillon, S et al

Poster (2015, April 12)

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See detailDimethylsulfoniopropionate (DMSP) cell quota of key Southern North Sea spring diatoms and Phaeocystis globosa
Speeckaert, Gaëlle ULg; Gypens, Nathalie; Lancelot, Christiane et al

Poster (2015, April)

Dimethylsulfide (DMS) in the ocean results of complex transformations of dimethylsulfoniopropionate (DMSP) produced by phytoplankton under different controls, including microbial transformation pathways ... [more ▼]

Dimethylsulfide (DMS) in the ocean results of complex transformations of dimethylsulfoniopropionate (DMSP) produced by phytoplankton under different controls, including microbial transformation pathways. The phytoplankton composition is an important factor of variability due to the species dependence of the DMSP production and conversion to DMS. To better appraise the link between phytoplankton diversity and the DMS(P) cycling in the Southern North Sea we present measurements of the DMSP cell quota of key spring phytoplankton species (Skeletonema costatum, Thalassiosira rotula, Rhizosolenia delicatula, Asterionella glacialis, Nitzschia closterium, Chaetoceros debilis, Chaetoceros socialis and Phaeocystis globosa) isolated from the North Sea and maintained in non-limiting and axenic laboratory culture conditions. Results are discussed with regards to literature data and hypothesis currently used in DMS(P) biogeochemical models. [less ▲]

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See detailApplications of stable isotopes in environmental studies at the University of Liege
Sturaro, Nicolas ULg; Borges, Alberto ULg; Das, Krishna ULg et al

Poster (2015, March 26)

Measurement and use of stable isotope ratios have a long history at the University of Liege (Belgium). Since at least 30 years, applications of stable isotopes in marine ecosystems have been developed ... [more ▼]

Measurement and use of stable isotope ratios have a long history at the University of Liege (Belgium). Since at least 30 years, applications of stable isotopes in marine ecosystems have been developed within the Laboratory of Oceanology and, more recently, within the Chemical Oceanography Unit. In the Laboratory of Oceanology, one research axis is the measurement of stable isotope composition (C, N, S) in organic matter to delineate trophic web structure and to study animal diet, their trophic niches and their alteration by human activities. This methodology has been successively applied worldwide in different habitats and ecosystems (marine, freshwater, terrestrial) in temperate and tropical areas. Mediterranean food web and fish trophic ecology have received a particular attention. Coupling between trophic ecology and ecotoxicology is another area of investigation. This has been applied mainly to marine vertebrates and freshwater ecosystems. Stable isotope labelling is also used in our laboratory to study and quantify various ecological processes such as inorganic nitrogen incorporation and trophic transfers. The laboratory facilities, renewed in 2012 and managed by Dr. Gilles Lepoint, are composed of an elemental analyser (EA, vario MICRO cube, Elementar) and a gas chromatography (GC, Agilent) coupled to an isotope ratio mass spectrometer (IRMS, Isoprime 100). The GC is also equipped with a quadrupole mass spectrometer. In 2014, the Chemical Oceanography Unit, headed by Dr. Alberto Borges, has acquired and implemented an off-axis cavity ring-down spectroscopy (CRDS) for the measurements of δ15Nα, δ15Nβ, δ18O of N2O. This enables characterization of the N2O origin in a variety of aquatic environments including groundwater in Wallonia, rivers and lakes in Wallonia and Africa, coastal environments (Scheldt estuary, Lake Grevelingen, North Sea), Mediterranean seagrass beds, and Antarctic and Arctic sea-ice. [less ▲]

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See detailInorhanic and organic carbon spatial variability in the Congo River during high waters (December 2013) and low waters (June 2014)
Borges, Alberto ULg; Bouillon, S; Teodoru, C et al

Conference (2015, February 23)

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See detailBiogeochemistry of the Congo River: annual transport fluxes and sources of carbon in the upper Congo River (Kisangani, DRC Congo)
Bouillon; Tambwe; Mambo, T et al

Conference (2015, February 22)

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See detailPlankton diversity and metabolism in the Congo River during high waters (December 2013) and low waters (June 2014)
Darchambeau, François ULg; Descy, JP; Leporcq, B et al

Poster (2015, February 22)

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See detailSediment and carbon dynamics in a tropical river-floodplain system during high-discharge conditions (Tana River, Kenya)
Geeraert, N; Omengo; Borges, Alberto ULg et al

Conference (2015, February 22)

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See detailCyanobacteria - the constructors of travertines?
Kleinteich, Julia; Stelmach Pessi, Igor ULg; Velazquez, David et al

Conference (2015, February)

Cyanobacteria are participating in carbonate build-up and travertine formation in the Belgian river Hoyoux and its tributaries. In this study, we sampled calcareous material from travertines and oncoliths ... [more ▼]

Cyanobacteria are participating in carbonate build-up and travertine formation in the Belgian river Hoyoux and its tributaries. In this study, we sampled calcareous material from travertines and oncoliths from four sampling sites on the Hoyoux river and Triffoy brook. In addition, the water chemistry was determined. The structure of the material was analyzed by Scanning Electron Microscopy and Raman microscopy (?°. The dominant cyanobacterial species was isolated and identified on the basis of microscopic observation and amplification of the 16S-ITS fragment as Phormidium sp., likely functioning as the ‘architect’ of the travertine system. In order to describe the full diversity of the travertine system and to discriminate between the active fraction and inactive or dead organic matter, DNA as well as RNA was extracted from the travertine material, amplified using cyanobacteria specific primers and sequenced by 454 pyrosequencing. To detect seasonal changes in the biological activity, summer and winter time points were compared. This study reveals the ecology of an overlooked environment in Belgian river systems and tries to explain the build-up of travertines. [less ▲]

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See detailThe variability of primary production in the ocean: from the synoptic to the global scale: The 45th International Liege Colloquium on Ocean Dynamics, Liege, Belgium, May 13-17, 2013
Grégoire, Marilaure ULg; Levy, Marina; Marra, John et al

Book published by Journal of Marine System, Elsevier Science (2015)

The 45th International Liege Colloquium on Ocean Dynamics (http://modb.oce.ulg.ac.be/colloquium/) gathered two hundreds scientists from around the world to discuss new insights related to the evaluation ... [more ▼]

The 45th International Liege Colloquium on Ocean Dynamics (http://modb.oce.ulg.ac.be/colloquium/) gathered two hundreds scientists from around the world to discuss new insights related to the evaluation of primary production at various spatial and temporal scales and in different regions of the world ocean (e.g. the polar and sea-ice region, the coastal and the deep ocean). Over the past two decades, substantial efforts were deployed to evaluate oceanic primary production. These efforts include in situ measurements of uptake rates using isotopic techniques, remote sensing, autonomous instrumentation for bio-optics, carbon or oxygen measurements, and the development of semi-empirical to complex biogeochemical models. The colloquium presented the opportunity to review the current knowledge in the estimation of primary production, and to assess the impact of physical processes on ocean productivity. Particular attention focused on the importance of physical processes at different spatial and temporal scales for controlling the level and variability of primary production and on the development of adequate methodologies to tackle this variability in order to derive large-scale, climate-driven budgets. Refined biogeochemical models considering for instance phytoplankton physiology, the representation of variable elemental stoichiometric ratios, the role of mixotrophy as well as satellite algorithms that are now able to simulate the plankton functional types are good candidates for scaling up. Contributions dealing with the difficult issue of interoperability of in-situ, satellite and modelling estimates of primary production were presented. Details on the terms of reference as well as the thematic session that were organized can be found at http://modb.oce.ulg.ac.be/?page=colloquium&year=2013. [less ▲]

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