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Imene Rouis-Zargouni Jean-Louis Turon Laurent Londeix Néjib Kallel Latifa Essallami 《Comptes Rendus Geoscience》2012,344(2):99-109
Using the analysis of dinoflagellate cysts in three deep-sea sediments cores situated in the Sicilian-Tunisian Strait, in the Gulf of Lions and in the Alboran Sea, we reconstruct the paleoenvironmental changes that took place during the last glacial-interglacial transition in the western Mediterranean Sea. The development of the warm microflora Impagidinium aculeatum and especially Spiniferites mirabilis appears to be an important proxy for recognizing warm periods as the Bölling/Alleröd and the Early Holocene. Bitectatodinium tepikiense, Spiniferites elongatus and Nematosphaeropsis labyrinthus mark the end of the Heinrich event 1 and the Younger Dryas. This cold microfloral association confirms the drastic climate changes in the western Mediterranean Sea synchronous to the dry and cold climate which occurred in the South European margin. The dinocyst N. labyrinthus shows high percentages in all studied regions during the Younger Dryas. Its distribution reveals a significant increase from the South to the North of this basin during this cold brief event. Thus, we note that this species can be considered as a new eco-stratigraphical tracer of the Younger Dryas in the western Mediterranean Sea. 相似文献
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Al Yacoubi Latifa Bouchaou Lhoussaine Jaillard Etienne Masrour Moussa Ait Brahim Yassine El Mouden Ahmed Schneider Jana Reichert Barbara 《Arabian Journal of Geosciences》2017,10(7):169
The Agadir-Essaouira area in the occidental High Atlas Mountains of Morocco is characterized by a semi-arid climate. The scarcity and quality of water resources, exacerbated by long drought periods, constitute a major problem for a sustainable development of this region. Groundwater resources of carbonate units within Jurassic and Cretaceous aquifers are requested for drinking and irrigation purposes. In this study, we collected 84 samples from wells, boreholes, springs, and rivers. Hydrochemical and isotopic data were used to examine the mineralization and origin of water, which control groundwater quality. The chemical composition of water seems to be controlled by water-rock interactions, such as dissolution of carbonates (calcite and dolomite), weathering of gypsum, as well as ion exchange processes, which explain the observed variability. Stable isotopes results show that groundwater from the mainly marly Cretaceous aquifer are submitted to an evaporation effect, while samples from the chiefly calcareous Jurassic aquifer indicate a meteoric origin, due to a rapid infiltration of recharge runoff through the karstic outcrops. The low values of δ18O and δ2H suggest a local recharge from areas with elevations ranging from 400 to 1200 m for the Cretaceous aquifer and from 800 to 1500 m for the Jurassic units. 相似文献
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The electrochemical oxidation of synthetic wastewater which contains biazo dye [amido black (AB)] on boron-doped diamond anode, “BDD anode,” was experimentally investigated to determine the influence of several operative parameters on the performance of the process. The study focalized on the effect of studied parameters on discoloration process and the degradation of the aromatic part of the dye molecule. Two distinct pathways with two different kinetics were observed. The decrease of pH improves the discoloration rate and the degradation of aromatic by-products after 90 min of electrolysis. The increase of current density has a considerable effect on discoloration and a little less effect on the aromatic derivative degradation. Hypochlorite electrogenerated from chloride addition exceptionally accelerates the discoloration, but it does not degrade aromatic derivatives as efficiently. It was observed that nitrates addition generates under electrolysis other derivates of AB as different colors than the dye one. The current efficiency depends very little on the initial pH; however, higher energy consumptions are obtained. 相似文献
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Fly ash is a product arising from coal combustion in thermal power plants. It represents a major source of environmental pollution. It is well known by its chemical composition rich of SiO2 and Al2O3. With the aim of preserving the environment against this contamination, fly ash was used along with the starting materials for producing glass cordierite (2MgO, 2Al2O3, 5SiO2). Four formulations were developed by mixing the silica gel, magnesium chloride (MgCl2.6H2O) and fly ash in the percentages enclosing the stoichiometry of cordierite (2MgO, 2Al2O3, 5SiO2). Different experimental techniques (DTA/TGA, X-ray diffraction, FTIR and SEM) were used to characterise the prepared formulations. The results shown that for all formulations, a cordierite phase was obtained at 1200 °C along with several secondary phases such as mullite, cristobalite, silicon oxide, enstatite and spinel. At 1300 °C, pure indialite (α-cordierite) was obtained along with a small amount of spinel. The four formulations sintered at 1200 °C exhibit a homogenous morphology and high porosity. The acicular-shaped indialite grains were observed in both formulations with excess of alumina and excess of magnesia. 相似文献
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