References of "Fagel, Nathalie"
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See detailCharacterization of clay from northern of Morocco for their industrial application
El Ouahabi, Meriam ULg; Fagel, Nathalie ULg

Poster (2010, May 04)

Clays are a natural resource used for millennia. Currently applications such as industrial minerals are diversified. In this context, our goal is to estimate the potential of the many clay deposits in ... [more ▼]

Clays are a natural resource used for millennia. Currently applications such as industrial minerals are diversified. In this context, our goal is to estimate the potential of the many clay deposits in northern of Morocco. The choice of this region is justified by the particular abundance of clay deposits used to manufacture building materials (brick, ceramic and refractories) and pottery. This study focuses on the mineralogical, chemical and geotechnical characterization tests carried out on Tangier-Tetouan and Meknes clays from northern of Morocco. The suitability of raw clay material from those regions in order to produce ceramic and brick has not been tested yet. The results revealed that the studied samples are diversified, kaolinite and illite (Tetouan clay) and kaolinite and illite and smectite and vermiculite (Tangier and Meknes clay) based materials. There were no major differences in grain-size distribution, whereas Meknes clay was more plastic than Tetouan-Tangier clay. The cation exchange capacity show that Meknes and Tangier clay were more important than Tetouan clay. Specific surface area and thermal analaysis complete this caracterization. It was found that almost all technological properties of the Meknes clay deposit are led to the manufacture of ceramic floor tile, and Tetouan-Tangier clay provide opportunities to making brick and ceramic floor. The Tetouan- Tangier and Meknes clay are a potential ceramic raw material for growing Morrocan ceramic tile and brick industries [less ▲]

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See detailBenthic remineralization in the northeast European continental margin (northern Bay of Biscay)
Suykens, Kim; Schmidt, Sabine; Delille, Bruno ULg et al

Poster (2010, May 02)

We report a data-set of sediment characteristics and biogeochemical fluxes at the water-sediment interface at the northeast European continental margin (northern Bay of Biscay). Cores were obtained in ... [more ▼]

We report a data-set of sediment characteristics and biogeochemical fluxes at the water-sediment interface at the northeast European continental margin (northern Bay of Biscay). Cores were obtained in June 2006, May 2007 and 2008, at 8 stations on the shelf break (120 to 180 m), and at 2 stations on the continental slope (520 m and 680 m). Sediment-water fluxes of dissolved oxygen (O2), total alkalinity (TA), nitrate (NO3-), and dissolved silicate (DSi) were measured at a total of 20 stations. Sediment characteristics include: grain size, chlorophyll-a (Chl-a) and phaeopigment (Phaeo) content, particulate organic (POC) and inorganic (PIC) carbon content, and 234Th and 210Pb activities. Sediments were sandy (fine to coarse) with organic matter (OM) (1.0 - 4.0 %) and Chl-a (0.01 - 0.95 µg g-1) contents comparable to previous publications in the same region, and a relatively high PIC fraction (0.8 - 10.2 %). Sediment-water O2 fluxes (-2.4 to -8.4 mmol O2 m-2 d-1) were low compared to other coastal environments and correlated well with OM and Chl-a content. 234Th activity profiles indicated that Chl-a sediment content (apparently the main driver of total benthic organic carbon degradation) was mainly controlled by physical mixing processes related to local hydrodynamics. The correlation between sediment-water fluxes of O2 and NO3- indicated a close coupling of nitrification/denitrification and total benthic organic carbon degradation. Dissolution of biogenic silica (0.05 to 0.95 mmol m-2 d-1) was uncoupled from organic carbon degradation, characterized by sediment-water O2 fluxes. The link between sediment-water fluxes of TA and O2 indicated metabolic driven dissolution ( 0.33 +/- 0.47 mmol m-2 d-1) of calcium carbonates (CaCO3) in the sediments which represented ~1 % of the pelagic calcification rates due to coccolithophores. These rates were below those reported in sediments of continental slopes and of the deep ocean, probably due to the high over-saturation with respect to CaCO3 of the water column overlying the continental shelf sediments of the northern Bay of Biscay. Rates of total benthic organic carbon degradation and CaCO3 dissolution were low compared to water column rates of primary production, aphotic community respiration and CaCO3 production obtained during the cruises. [less ▲]

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See detailSpatio-temporal natural and anthropogenic environmental variability during the last 1500yrs in an ombrotrophic bog (East Belgium).
De Vleeschouwer, François; Fagel, Nathalie ULg; Allan, Mohamed et al

Poster (2010)

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See detailMutliproxy investigation of climatic and anthropogenic changes in a Baltic bog (N. Poland) during the last millennium
De Vleeschouwer, François; Fagel, Nathalie ULg; Piotrowska, Natalia et al

Poster (2010)

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See detailBulk organic geochemistry of sediments from Puyehue Lake and its watershed (Chile, 40°S): Implications for paleoenvironmental reconstructions
Bertrand, Sébastien; Sterken, Mieke; Vargas-Ramirez, Lourdes et al

in Palaeogeography, Palaeoclimatology, Palaeoecology (2010), 294

Since the last deglaciation, the mid-latitudes of the southern Hemisphere have undergone considerable environmental changes. In order to better understand the response of continental ecosystems to ... [more ▼]

Since the last deglaciation, the mid-latitudes of the southern Hemisphere have undergone considerable environmental changes. In order to better understand the response of continental ecosystems to paleoclimate changes in southern South America, we investigated the sedimentary record of Puyehue Lake, located in the western piedmont of the Andes in South-Central Chile (40°S). We analyzed the elemental (C, N) and stable isotopic ([delta]13C, [delta]15N) composition of the sedimentary organic matter preserved in the lake and its watershed to estimate the relative changes in the sources of sedimentary organic carbon through space and time. The geochemical signature of the aquatic and terrestrial end-members was determined on samples of lake particulate organic matter (N/C: 0.130) and Holocene paleosols (N/C: 0.069), respectively. A simple mixing equation based on the N/C ratio of these end-members was then used to estimate the fraction of terrestrial carbon ([latin small letter f with hook]T) preserved in the lake sediments. Our approach was validated using surface sediment samples, which show a strong relation between [latin small letter f with hook]T and distance to the main rivers and to the shore. We further applied this equation to an 11.22 m long sediment core to reconstruct paleoenvironmental changes in Puyehue Lake and its watershed during the last 17.9 kyr. Our data provide evidence for a first warming pulse at 17.3 cal kyr BP, which triggered a rapid increase in lake diatom productivity, lagging the start of a similar increase in sea surface temperature (SST) off Chile by 1500 years. This delay is best explained by the presence of a large glacier in the lake watershed, which delayed the response time of the terrestrial proxies and limited the concomitant expansion of the vegetation in the lake watershed (low [latin small letter f with hook]T). A second warming pulse at 12.8 cal kyr BP is inferred from an increase in lake productivity and a major expansion of the vegetation in the lake watershed, demonstrating that the Puyehue glacier had considerably retreated from the watershed. This second warming pulse is synchronous with a 2 °C increase in SST off the coast of Chile, and its timing corresponds to the beginning of the Younger Dryas Chronozone. These results contribute to the mounting evidence that the climate in the mid-latitudes of the southern Hemisphere was warming during the Younger Dryas Chronozone, in agreement with the bipolar see-saw hypothesis. [less ▲]

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See detailComparative influence of burial depth on the clay mineral assemblage of the Agadir-Essaouira basin (western High Atlas, Morocco)
Daoudi, Lachen; Ouajhain, B.; Rocha, F. et al

in Clay Minerals (2010), 45(4), 453-467

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See detailLate Holocene environmental changes inferred from diatom, chironomid, and pollen assemblages in an Andean lake in Central Chile, Lake Laja (36°S)
Urrutia, Roberto; Araneda, Alberto; Torres, Laura et al

in Hydrobiologia (2010), 648

A sediment core encompassing the last 2000 years was extracted from Lake Laja, Chile, (36°54′S, 71°05′W) using an Uwitec drilling platform. The sediment was subsampled for loss on ignition, nutrients ... [more ▼]

A sediment core encompassing the last 2000 years was extracted from Lake Laja, Chile, (36°54′S, 71°05′W) using an Uwitec drilling platform. The sediment was subsampled for loss on ignition, nutrients, biogenic silica, and biological proxies (diatoms, chironomids, pollen). The sedimentary profile was characterized by several coarse volcanic layers. Loss on ignition, nutrients, and biogenic silica showed an increasing trend that suggests a recent shift to a higher trophic status. Diatom assemblages also suggested higher nutrient content with increased abundances of Aulacoseira granulata, A. distans, and Asterionella formosa. At the same time, a marked change in the benthic and facultative planktonic taxa may be associated with cooling. This period of change coincides with the European Little Ice Age (LIA). The chironomid profile showed four key zones distinguished largely by changes in the abundance of Tanytarsini, Parachironomus, and Macropelopia. Like diatoms, chironomids also seemed to reflect a shift to higher trophic conditions in the upper part reflected by increasing abundance of taxa such as Tribelos/Phaenopsectra, Cricotopus/Orthocladius, and Ablabesmyia. The most striking feature in the chironomid assemblage is the abundance of Podonominae, Parapsectrocladius, and Limnophyes/Compterosmittia, which could be associated with a cold-dry period between 1500 and 1900 AD in Lake Laja (the period of the European LIA). Pollen assemblages indicated fluctuations in humidity through changes in Nothofagus dombeyi-type, Poaceae, and Ephedra, and we inferred a strong human impact over the last 100 years from the appearance of Plantago and increased levels of Poaceae and Asteraceae subf. Cichorioidae. Finally, the three proxies showed the occurrence of a cold-dry event in Lake Laja (~1550–1900 AD), which roughly coincides with the European LIA. However the data from this research, does not prove neither rejects the existence of the occurrence of the MWP in the central Andes. [less ▲]

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See detailDiagenèse osseuse et genèse de nodules phosphatés, associés aux sédiments fluvio-lacustres de sites à hominidés miocène (Kenya)
DERICQUEBOURG, P.; PERSON, A.; SEGALEN, L. et al

Poster (2010)

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See detailBenthic remineralisation in the Northeast European Continental margin (Northern Biscay Bay)
Suykens, K.; Schmidt, S.; Delille, Bruno ULg et al

Poster (2010)

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See detailA paleorecord of atmospheric lead deposition in France. New data from “La Godivelle” peat bog (Puy de Dôme)
De vleeschouwer, F.; Mattielli, N.; Renson, V. et al

Poster (2010)

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See detailAtmospheric lead deposition in an ombrotrophic peat bog of Southern Poland
Fiałkiewicz-Kozieł, B.; De Vleeschouwer, F.; Smieja-Król, B. et al

Poster (2010)

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See detailA 14,000 yr elemental and lead isotopis record in a peat core in the south of Poland –results and interpretation
Tudyka, K.; De Vleeschouwer, F.; Pazdur, A. et al

Poster (2010)

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See detailTraces metal inputs in the Misten bog (East Belgium): Level of contamination and spatial variability
Allan, M.; Fagel, Nathalie ULg; De Vleeschouwer, F. et al

Poster (2010)

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See detailEnvironmental changes in two lakes of Northern Patagonia (Chile): A 1000 yr reconstruction based on pollen and charcoal.
Vargas, N.; Torres, L.; Araneda, A. et al

Poster (2010)

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See detailLate Holocene environmental changes recorded in the sediments of Lago Thompson, Northern Chilean Patagonia
Fagel, Nathalie ULg; Nuttin, L.; Bertrand, S. et al

Poster (2010)

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