Self-sealing of fractures in the indurated Callovo-Oxfordian(COX)and Opalinus(OPA)claystones,which are considered as host rocks for disposal of radioactive waste,was investigated on artificially fractured samples.The ...Self-sealing of fractures in the indurated Callovo-Oxfordian(COX)and Opalinus(OPA)claystones,which are considered as host rocks for disposal of radioactive waste,was investigated on artificially fractured samples.The samples were extracted from four lithological facies relatively rich in clay mineral,carbonate and quartz,respectively.The self-sealing of fractures was measured by fracture closure,water permeability variation,gas penetration,and recovery of gas-induced pathways.Most of the fractured samples exhibited a dramatic reduction inwater permeability to low levels that is close to that of intact rock,depending on their mineralogical composition,fracture intensity,confining stress,and load duration.The self-sealing capacity of the clay-rich samples is higher than that of the carbonate-rich and sandy ones.Significant effects of sample size and fracture intensity were identified.The sealed fractures become gas-tight for certain in-jection pressures.However,the measured gas breakthrough pressures are still lower than the confining stresses.The gas-induced pathways can recover when contacting water.These important findings imply that fractures in such indurated claystones can effectively recover to hinder water transport but allow gas release under relatively low pressures without compromising the rock integrity.展开更多
Thermal effects on the Callovo-Oxfordian and Opalinus clay rocks for hosting high-level radioactive waste were comprehensively investigated with laboratory and in situ experiments under repository relevant conditions:...Thermal effects on the Callovo-Oxfordian and Opalinus clay rocks for hosting high-level radioactive waste were comprehensively investigated with laboratory and in situ experiments under repository relevant conditions:(1) stresses covering the range from the initial lithostatic state to redistributed levels after excavation,(2) hydraulic drained and undrained boundaries, and(3) heating from ambient temperature up to 90℃-120℃ and a subsequent cooling phase. The laboratory experiments were performed on normal-sized and large hollow cylindrical samples in various respects of thermal expansion and contraction, thermally-induced pore water pressure, temperature influences on deformation and strength, thermal impacts on swelling, fracture sealing and permeability. The laboratory results obtained from the samples are consistent with the in situ observations during heating experiments in the underground research laboratories at Bure and Mont-Terri. Even though the claystones showed significant responses to thermal loading, no negative effects on their favorable barrier properties were observed.展开更多
In the context of the Cigeo project,the French National Radioactive Waste Management Agency(Andra)is studying the behaviour of a deep geological facility for radioactive waste deposit in the CallovoOxfordian(COx)clays...In the context of the Cigeo project,the French National Radioactive Waste Management Agency(Andra)is studying the behaviour of a deep geological facility for radioactive waste deposit in the CallovoOxfordian(COx)claystone.The assessment of durability of this project requires the prediction of irreversible strain over a large time scale.The mechanical interaction of the host rock and the concrete support of tunnels must be investigated to ensure the long-term sustainability of the structure.The instantaneous and time-dependent behaviour of the claystone-concrete interface is experimentally investigated with direct shear tests and long-duration shear tests of a few months.The mechanical and structural state of the claystone which is affected after interaction with concrete reflects to the response of the claystone-concrete interface,and thus different types of COx claystone-concrete interfaces are tested.The delayed deformation of the interface is found to be linked to the level of the normal loading and the loading history while a different response of the interface was observed from the short-and long-duration tests,indicating a possible progressive modification of interface under long-duration loadings.展开更多
Urban sediment generated by stormwater management techniques are highly contaminated with various trace elements. The characterization of trace element speciation and mobility are critical information to improve envir...Urban sediment generated by stormwater management techniques are highly contaminated with various trace elements. The characterization of trace element speciation and mobility are critical information to improve environmental risk assessment. This study investigates the spatial and temporal variability of major and trace element release from a sedimentary layer in Django Reinhart stormwater infiltration basin (Chassieu, eastern suburbs of Lyon, France). Sampling was conducted for 3 zones and two dates. Chemical characterization was performed (X-Ray diffraction, ICP-AES). The samples were submitted to Acid Neutralization Capacity & Base Neutralization Capacity ANC-BNC tests, according to European standard 14429 (AFNOR, 2015). Solid matrices were mixed with acid or basic solutions and physicochemical parameters and major and trace element release (i.e. Al, Ca, Fe, P, S, Si, Cu, Zn and total carbon) were followed as a function of pH. The results show that the urban sediment has no significant spatial and temporal variability with regards to element release. This observation is all the more surprising that the samples were collected in three contrasting zones regarding stormwater supply and hydric conditions. Element release follows the same trends as a function of pH with a bell-shaped solubilization curve exhibiting with the highest solubility at extreme pH values. However, the samples showed slight differences concerning the release of major elements. Such differences are related to slight differences in total mineral contents (organic matter, carbonates…) and chemical composition of the sediments. The results show that despite the varying environmental conditions, the sediment chemical properties can be considered as very stable and uniform over space, depending mainly on the local geochemical context and watershed characteristics. This study highlights the strength and affluence of the information obtained by ANC-BNC tests on the release of major and traces metal elements by urban sediments and brings relevant information regarding the management of these sediments.展开更多
Catfishes belonging to the genus <em>Chrysichthys</em> are generally important fish species in inland water bodies of Africa because of their high commercial value. Among them, <em>C.</em> <...Catfishes belonging to the genus <em>Chrysichthys</em> are generally important fish species in inland water bodies of Africa because of their high commercial value. Among them, <em>C.</em> <em>nigrodigitatus</em> could represent, at certain periods of the year the highest biomass of the littoral ichthyofauna, accounting for 17 to 43.8% of total catches. In this paper, its diet in the hydrosystem Lake Togo-Lagoon of Aného was investigated focusing on how differences in diet and food consumption are related to size, season and sexual maturity. A total of 195 males and 137 females were sampled from January to December 2017. The digestive tract of each individual was dissected and its content was analyzed, using indexes of stomach contents analysis method. Diet variability in relation to season and biometric <em></em>parameters was also studied. About 99 stomachs were empty with an overall vacuity index of 29.82%. However, vacuity index was found to vary in relation to fish size and months. The fish has been found to be omnivorous with a carnivorous tendency consuming a wide range of prey items (H = 3.34). Juvenile and adult freshwater clams (<em>Galatea paradoxa</em>) were the numerical dominant preys (%N = 44%) while the penaeid shrimps (<em>Farfantepenaeus notialis</em>) with an annual frequency of occurrence (Fo) of 49.36% and all species confused of fish (33.91%) were the most preferred preys. The index of relative importance (IRI) reveals that freshwater clam (40.49%), penaeid shrimps (35.85%) and all species confused of fish (14.58%) were the most important preys of <em>C. nigrodigitatus</em>. The dominance of Malacostraca and Mollusca in the diet of <em>C. nigrodigitatus</em> in the hydrosystem Lake Togo-Lagoon of Aného is likely one of the more important considerations for future management plans.展开更多
Geopolymers are an alternative to Portland cement, well known for their contribution to greenhouse gas emissions. Finding materials that can validly replace Portland cement is a challenge. It is in this logic that thi...Geopolymers are an alternative to Portland cement, well known for their contribution to greenhouse gas emissions. Finding materials that can validly replace Portland cement is a challenge. It is in this logic that this work was undertaken with the objective of characterizing two local clay resources of Togo as raw materials for geopolymers. The physico-chemical properties of these clays were determined by characterization using X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric (TGA) and elemental analysis (ICP-OES). The results show that these clays contain kaolinite and therefore can be used in the formulation of geopolymers. The characterized clays underwent heat treatments transforming the crystalline phases into more reactive amorphous phases and then were activated by an alkaline solution in order to formulate the geopolymer materials. These elaborated materials were analyzed by Fourier transform infrared to identify the types of bonds formed. The results of these analyses show that these two local clays are well suited to be used in synthesizing geopolymers. Our future work will focus on the constraints of consolidation as well as the mechanical properties of these geopolymer materials.展开更多
In the framework of various phosphates discharges valorization, we have realized physicochemical and mineralogical characterizations of these discharges. We have undertaken the physicochemical and mineralogical charac...In the framework of various phosphates discharges valorization, we have realized physicochemical and mineralogical characterizations of these discharges. We have undertaken the physicochemical and mineralogical characterizations of this waste by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), thermal analysis and Atomic Emission Spectrometry Coupled to an Inductive Plasma Source. The results of these analyze show that phosphate sludge and screen rejects could be used in ceramics, in the manufacture of aggregates, in agriculture and other fields. On the other hand, rich magnetic waste could be used in heterogeneous photocatalysis in waste liquids treatment.展开更多
Due to its rapid movement, preferential flow (PF) in the vadose zone allows much faster contaminant transport, which may have a significant impact on ground-water quality. PF can occur in heterogeneous vadose zones an...Due to its rapid movement, preferential flow (PF) in the vadose zone allows much faster contaminant transport, which may have a significant impact on ground-water quality. PF can occur in heterogeneous vadose zones and it strongly depends on hydric and hydraulic conditions like entering flow rates at surface. This study deals with the modeling of the establishment of PF, and related solute transfer during the infiltration phase in a strongly heterogeneous glaciofluvial deposit. This deposit is made of four contrasting lithofacies (sand, gravel, bimodal gravel and matrix-free gravel) and lies underneath an urban infiltration basin (Lyon, France). Previous studies have been carried out on this site and linked the regionalization of soil pollution with the lithological heterogeneity. But none of them clearly demonstrated how heterogeneity could impact flow and solute transfer and may explain such a regionalization. In this study, we model flow and solute transfer at the trench scale for both uniform and heterogeneous profiles in order to characterize the effect of lithological heterogeneity. In addition, such a modeling was performed for two different entering flow rates to depict the influence of condition at surface on PF. A key result is that heterogeneity clearly impacts unsaturated flow and solute transfer. Numerical modeling permitted pointing out the existence of PF paths associated with the sedimentary heterogeneity of the glaciofluvial deposit. For lower surface fluxes, the sand lens and matrix-free gravel were the sources of capillary barrier effects, leading to a funneled flow and a groundwater recharge characterized by earlier and more dispersed wetting fronts. Such a flow pattern enhances solutes transfer and reduces solute retention by soil. Thus, the effect of heterogeneity on solute transfer is significant, especially for the most reactive solutes.展开更多
The main cash crop in Togo is cotton, with about 70% of agricultural exports. This crop is very dependent on the use of chemical inputs, in particular pesticides. Pesticides used in cotton farming in Togo include orga...The main cash crop in Togo is cotton, with about 70% of agricultural exports. This crop is very dependent on the use of chemical inputs, in particular pesticides. Pesticides used in cotton farming in Togo include organochlorines, triazines, organophosphates and pyrethroids. We conducted a study on the impact of these pesticide use, in particular organochlorines and triazines, on cotton farming soils. We chose the Plateaux region (southern Togo) as the study area because of its high cotton production. Analysis was carried out on crop soil samples at the 0 - 20 cm horizon. Several pesticide residues were found: simazine (0.051 to 0.103 μg/Kg soil);atrazine (0.149 to 0.197 μg/Kg soil);lindane (0.259 to 0.672 μg/Kg soil);β-endosulfan (1.37 to 5.727 μg/Kg soil);dieldrin (0.063 to 1.16 μg/Kg soil);endrin (0.512 μg/Kg soil), Heptachlor (0.489 to 1.243 μg/Kg soil);Heptachlor epoxide (0.928 to 1.633 μg/Kg soil);[2,4'DDT] (0.257 μg/Kg soil);[4,4'DDE] (0.262 μg/Kg soil). These results show pesticide contamination of cotton farming soils.展开更多
</span><i><span style="font-family:Verdana;">Achatina</span></i> <i><span style="font-family:Verdana;">togoensis</span></i><span style="...</span><i><span style="font-family:Verdana;">Achatina</span></i> <i><span style="font-family:Verdana;">togoensis</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:""><span style="font-family:Verdana;"> is a giant land snail taxa endemic to the northern sectors of the Monts Togo, which has been regarded as full species or subspecies of the highly variable, widespread </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">achatina</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:Verdana;"> (L.). To address this issue, samples of snails were taken throughout the distribution range of the two taxa in the Dahomey Gap (West Africa) and separated into 112 </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">achatina</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:Verdana;"> and 141 </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">togoensis</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:Verdana;"> according to color of </span></span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">columella and parietal wall. Radulae were compared and shell characters of these 2 species were evaluated through </span><span style="font-family:Verdana;">the </span><span style="font-family:""><span style="font-family:Verdana;">traditional morphometric method. The results indicate that the species cannot be distinguished by overall shell size and radular morphology, but they exhibit significant differences in shell shape and meristic traits. The typical </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">achatina</span></i><span style="font-family:Verdana;"></i></span></span></span><span style="font-family:""> </span><span style="font-family:Verdana;">with vinaceous-red columella</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">has a low-spired shell and an expanded aperture (globose shape) whereas </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">togoensis</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:Verdana;"> has a higher-spired and smaller aperture (a fusiform shape). We suggest that local environmental effects are probably the causes of morphological divergence between the two taxa. It is likely that peripheral populations of the typical form of </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">achatina</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:Verdana;"> would have isolated and developed in the drier facies of the humid forest that individualized in the northern sector of the mountains after the arid or interpluvial period of Holocene. In addition, we find that </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">togoensis</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:Verdana;"> meets the criteria B2ab</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">(ii, iii) to categorize as “Endangered”. However, whether this latter should be considered as separate species cannot be decided at the current state of knowledge.展开更多
The omnivorous fish species, <i>C. nigrodigitatus</i> feeds mainly on benthic organisms and may therefore consume contaminated food throughout its food web. This can lead to the bioaccumulation of contamin...The omnivorous fish species, <i>C. nigrodigitatus</i> feeds mainly on benthic organisms and may therefore consume contaminated food throughout its food web. This can lead to the bioaccumulation of contaminants such as trace elements in their tissues. However, fish consumption is a major pathway of human exposure to contaminants which may cause public health problems. The aim of the present study is to assess trace elements contamination in some species from the food web of <i>C. nigrodigitatus</i>. For this, 10 main food items of the silver catfish were collected at two sites from February to July 2017 and analyzed using an Atomic Absorption Spectrometer coupled with a hydride and cold vapour generator. The concentrations of trace elements varied greatly from one species to another and within each species. These values ranged from 0.007 mg/kg for Hg in C hippos to 354.84 mg/kg for Mn in <i>P. fusca</i>. The most contaminated species by trace elements were benthic organisms: <i>M. perna</i> (Cd, Pb, Hg), <i>Pagurus</i> sp. (Cr, Ni, Cu, Zn), <i>G. paradoxa</i> (As) and <i>P. fusca</i> (Mn). The average concentrations of trace elements found in species were, for the most part, above WHO standards except Hg in <i>M. perna</i> and <i>G. paradoxa</i>. The water-based bioconcentration factors (BCFw) reach 92.58 for Cd, 44.72 for Pb, 382.49 for Hg and 1514.34 for As in <i>M. perna</i>. It is therefore necessary to pay particular attention to this ecosystem and to put in place a better management plan.展开更多
Green coal or bio-coal is coal produced with rich biodegradable materials, elaborated from agricultural and household residues with a high percentage of carbon. This green charcoal (fuel briquettes) is an alternative ...Green coal or bio-coal is coal produced with rich biodegradable materials, elaborated from agricultural and household residues with a high percentage of carbon. This green charcoal (fuel briquettes) is an alternative to charcoal. Well known for its contribution to greenhouse gas emissions, charcoal is one of the causes of tree felling. The valorization of waste by the manufacture of biofuels could be an alternative to the use of charcoal. The general objective of the present study is the valorization of nine biomasses from Togo as raw materials. Specifically, physico-chemical characteristics such as dehydration, acidity, and conductivity were determined. Information on the structure and composition of the biomass was found. These data on the nature of the biomass were found through the use of Fourier Transform Infrared (FTIR) and Thermogravimetry (TGA). The promising results inform on the nature of the analyzed samples and allow the selection of the best biomass which would give an important thermal conductivity for the manufacture of the briquettes, but also of the binders to be used according to the physico-chemical characteristics like the pH.展开更多
The objective of this work was to determine the suitability of poultry methacompost from the 2nd methanizer of the BRIN FOUNDATION in Yaokokoroko (Bondoukou, Côte d’Ivoire), to be used in the improvement of soil...The objective of this work was to determine the suitability of poultry methacompost from the 2nd methanizer of the BRIN FOUNDATION in Yaokokoroko (Bondoukou, Côte d’Ivoire), to be used in the improvement of soil fertility. The methacompost studied has a C/N ratio = 17.26, which could characterize a stable methacompost with high amending power. It also contains mineral elements Nitrogen (N) = 0.68% DM;Phosphorus (P) = 0.084% DM;Potassium (K) = 0.67% DM;Calcium (Ca) = 0.65% DM;Magnesium (Mg) = 0.15% DM. red in the standard relating to the organic amendments (NFU 44-051). The methacompost has fertilizing and amending properties and could not present any risk for vegetation and soils.展开更多
基金This work was co-funded by the German Federal Ministry for Economic Affairs and Energy(BMWi)under contract number 02E11627by the European Commission(EC)from the Euro-pean Union’s Horizon 2020 research and innovationprogram under Grant No.847593.
文摘Self-sealing of fractures in the indurated Callovo-Oxfordian(COX)and Opalinus(OPA)claystones,which are considered as host rocks for disposal of radioactive waste,was investigated on artificially fractured samples.The samples were extracted from four lithological facies relatively rich in clay mineral,carbonate and quartz,respectively.The self-sealing of fractures was measured by fracture closure,water permeability variation,gas penetration,and recovery of gas-induced pathways.Most of the fractured samples exhibited a dramatic reduction inwater permeability to low levels that is close to that of intact rock,depending on their mineralogical composition,fracture intensity,confining stress,and load duration.The self-sealing capacity of the clay-rich samples is higher than that of the carbonate-rich and sandy ones.Significant effects of sample size and fracture intensity were identified.The sealed fractures become gas-tight for certain in-jection pressures.However,the measured gas breakthrough pressures are still lower than the confining stresses.The gas-induced pathways can recover when contacting water.These important findings imply that fractures in such indurated claystones can effectively recover to hinder water transport but allow gas release under relatively low pressures without compromising the rock integrity.
基金funding by the German Federal Ministry of Economics and Technology (BMWi) under contract No.02E10377the French National Radioactive Waste Management Agency (Andra)
文摘Thermal effects on the Callovo-Oxfordian and Opalinus clay rocks for hosting high-level radioactive waste were comprehensively investigated with laboratory and in situ experiments under repository relevant conditions:(1) stresses covering the range from the initial lithostatic state to redistributed levels after excavation,(2) hydraulic drained and undrained boundaries, and(3) heating from ambient temperature up to 90℃-120℃ and a subsequent cooling phase. The laboratory experiments were performed on normal-sized and large hollow cylindrical samples in various respects of thermal expansion and contraction, thermally-induced pore water pressure, temperature influences on deformation and strength, thermal impacts on swelling, fracture sealing and permeability. The laboratory results obtained from the samples are consistent with the in situ observations during heating experiments in the underground research laboratories at Bure and Mont-Terri. Even though the claystones showed significant responses to thermal loading, no negative effects on their favorable barrier properties were observed.
文摘In the context of the Cigeo project,the French National Radioactive Waste Management Agency(Andra)is studying the behaviour of a deep geological facility for radioactive waste deposit in the CallovoOxfordian(COx)claystone.The assessment of durability of this project requires the prediction of irreversible strain over a large time scale.The mechanical interaction of the host rock and the concrete support of tunnels must be investigated to ensure the long-term sustainability of the structure.The instantaneous and time-dependent behaviour of the claystone-concrete interface is experimentally investigated with direct shear tests and long-duration shear tests of a few months.The mechanical and structural state of the claystone which is affected after interaction with concrete reflects to the response of the claystone-concrete interface,and thus different types of COx claystone-concrete interfaces are tested.The delayed deformation of the interface is found to be linked to the level of the normal loading and the loading history while a different response of the interface was observed from the short-and long-duration tests,indicating a possible progressive modification of interface under long-duration loadings.
文摘Urban sediment generated by stormwater management techniques are highly contaminated with various trace elements. The characterization of trace element speciation and mobility are critical information to improve environmental risk assessment. This study investigates the spatial and temporal variability of major and trace element release from a sedimentary layer in Django Reinhart stormwater infiltration basin (Chassieu, eastern suburbs of Lyon, France). Sampling was conducted for 3 zones and two dates. Chemical characterization was performed (X-Ray diffraction, ICP-AES). The samples were submitted to Acid Neutralization Capacity & Base Neutralization Capacity ANC-BNC tests, according to European standard 14429 (AFNOR, 2015). Solid matrices were mixed with acid or basic solutions and physicochemical parameters and major and trace element release (i.e. Al, Ca, Fe, P, S, Si, Cu, Zn and total carbon) were followed as a function of pH. The results show that the urban sediment has no significant spatial and temporal variability with regards to element release. This observation is all the more surprising that the samples were collected in three contrasting zones regarding stormwater supply and hydric conditions. Element release follows the same trends as a function of pH with a bell-shaped solubilization curve exhibiting with the highest solubility at extreme pH values. However, the samples showed slight differences concerning the release of major elements. Such differences are related to slight differences in total mineral contents (organic matter, carbonates…) and chemical composition of the sediments. The results show that despite the varying environmental conditions, the sediment chemical properties can be considered as very stable and uniform over space, depending mainly on the local geochemical context and watershed characteristics. This study highlights the strength and affluence of the information obtained by ANC-BNC tests on the release of major and traces metal elements by urban sediments and brings relevant information regarding the management of these sediments.
文摘Catfishes belonging to the genus <em>Chrysichthys</em> are generally important fish species in inland water bodies of Africa because of their high commercial value. Among them, <em>C.</em> <em>nigrodigitatus</em> could represent, at certain periods of the year the highest biomass of the littoral ichthyofauna, accounting for 17 to 43.8% of total catches. In this paper, its diet in the hydrosystem Lake Togo-Lagoon of Aného was investigated focusing on how differences in diet and food consumption are related to size, season and sexual maturity. A total of 195 males and 137 females were sampled from January to December 2017. The digestive tract of each individual was dissected and its content was analyzed, using indexes of stomach contents analysis method. Diet variability in relation to season and biometric <em></em>parameters was also studied. About 99 stomachs were empty with an overall vacuity index of 29.82%. However, vacuity index was found to vary in relation to fish size and months. The fish has been found to be omnivorous with a carnivorous tendency consuming a wide range of prey items (H = 3.34). Juvenile and adult freshwater clams (<em>Galatea paradoxa</em>) were the numerical dominant preys (%N = 44%) while the penaeid shrimps (<em>Farfantepenaeus notialis</em>) with an annual frequency of occurrence (Fo) of 49.36% and all species confused of fish (33.91%) were the most preferred preys. The index of relative importance (IRI) reveals that freshwater clam (40.49%), penaeid shrimps (35.85%) and all species confused of fish (14.58%) were the most important preys of <em>C. nigrodigitatus</em>. The dominance of Malacostraca and Mollusca in the diet of <em>C. nigrodigitatus</em> in the hydrosystem Lake Togo-Lagoon of Aného is likely one of the more important considerations for future management plans.
文摘Geopolymers are an alternative to Portland cement, well known for their contribution to greenhouse gas emissions. Finding materials that can validly replace Portland cement is a challenge. It is in this logic that this work was undertaken with the objective of characterizing two local clay resources of Togo as raw materials for geopolymers. The physico-chemical properties of these clays were determined by characterization using X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric (TGA) and elemental analysis (ICP-OES). The results show that these clays contain kaolinite and therefore can be used in the formulation of geopolymers. The characterized clays underwent heat treatments transforming the crystalline phases into more reactive amorphous phases and then were activated by an alkaline solution in order to formulate the geopolymer materials. These elaborated materials were analyzed by Fourier transform infrared to identify the types of bonds formed. The results of these analyses show that these two local clays are well suited to be used in synthesizing geopolymers. Our future work will focus on the constraints of consolidation as well as the mechanical properties of these geopolymer materials.
文摘In the framework of various phosphates discharges valorization, we have realized physicochemical and mineralogical characterizations of these discharges. We have undertaken the physicochemical and mineralogical characterizations of this waste by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), thermal analysis and Atomic Emission Spectrometry Coupled to an Inductive Plasma Source. The results of these analyze show that phosphate sludge and screen rejects could be used in ceramics, in the manufacture of aggregates, in agriculture and other fields. On the other hand, rich magnetic waste could be used in heterogeneous photocatalysis in waste liquids treatment.
文摘Due to its rapid movement, preferential flow (PF) in the vadose zone allows much faster contaminant transport, which may have a significant impact on ground-water quality. PF can occur in heterogeneous vadose zones and it strongly depends on hydric and hydraulic conditions like entering flow rates at surface. This study deals with the modeling of the establishment of PF, and related solute transfer during the infiltration phase in a strongly heterogeneous glaciofluvial deposit. This deposit is made of four contrasting lithofacies (sand, gravel, bimodal gravel and matrix-free gravel) and lies underneath an urban infiltration basin (Lyon, France). Previous studies have been carried out on this site and linked the regionalization of soil pollution with the lithological heterogeneity. But none of them clearly demonstrated how heterogeneity could impact flow and solute transfer and may explain such a regionalization. In this study, we model flow and solute transfer at the trench scale for both uniform and heterogeneous profiles in order to characterize the effect of lithological heterogeneity. In addition, such a modeling was performed for two different entering flow rates to depict the influence of condition at surface on PF. A key result is that heterogeneity clearly impacts unsaturated flow and solute transfer. Numerical modeling permitted pointing out the existence of PF paths associated with the sedimentary heterogeneity of the glaciofluvial deposit. For lower surface fluxes, the sand lens and matrix-free gravel were the sources of capillary barrier effects, leading to a funneled flow and a groundwater recharge characterized by earlier and more dispersed wetting fronts. Such a flow pattern enhances solutes transfer and reduces solute retention by soil. Thus, the effect of heterogeneity on solute transfer is significant, especially for the most reactive solutes.
文摘The main cash crop in Togo is cotton, with about 70% of agricultural exports. This crop is very dependent on the use of chemical inputs, in particular pesticides. Pesticides used in cotton farming in Togo include organochlorines, triazines, organophosphates and pyrethroids. We conducted a study on the impact of these pesticide use, in particular organochlorines and triazines, on cotton farming soils. We chose the Plateaux region (southern Togo) as the study area because of its high cotton production. Analysis was carried out on crop soil samples at the 0 - 20 cm horizon. Several pesticide residues were found: simazine (0.051 to 0.103 μg/Kg soil);atrazine (0.149 to 0.197 μg/Kg soil);lindane (0.259 to 0.672 μg/Kg soil);β-endosulfan (1.37 to 5.727 μg/Kg soil);dieldrin (0.063 to 1.16 μg/Kg soil);endrin (0.512 μg/Kg soil), Heptachlor (0.489 to 1.243 μg/Kg soil);Heptachlor epoxide (0.928 to 1.633 μg/Kg soil);[2,4'DDT] (0.257 μg/Kg soil);[4,4'DDE] (0.262 μg/Kg soil). These results show pesticide contamination of cotton farming soils.
文摘</span><i><span style="font-family:Verdana;">Achatina</span></i> <i><span style="font-family:Verdana;">togoensis</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:""><span style="font-family:Verdana;"> is a giant land snail taxa endemic to the northern sectors of the Monts Togo, which has been regarded as full species or subspecies of the highly variable, widespread </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">achatina</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:Verdana;"> (L.). To address this issue, samples of snails were taken throughout the distribution range of the two taxa in the Dahomey Gap (West Africa) and separated into 112 </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">achatina</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:Verdana;"> and 141 </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">togoensis</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:Verdana;"> according to color of </span></span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">columella and parietal wall. Radulae were compared and shell characters of these 2 species were evaluated through </span><span style="font-family:Verdana;">the </span><span style="font-family:""><span style="font-family:Verdana;">traditional morphometric method. The results indicate that the species cannot be distinguished by overall shell size and radular morphology, but they exhibit significant differences in shell shape and meristic traits. The typical </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">achatina</span></i><span style="font-family:Verdana;"></i></span></span></span><span style="font-family:""> </span><span style="font-family:Verdana;">with vinaceous-red columella</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">has a low-spired shell and an expanded aperture (globose shape) whereas </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">togoensis</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:Verdana;"> has a higher-spired and smaller aperture (a fusiform shape). We suggest that local environmental effects are probably the causes of morphological divergence between the two taxa. It is likely that peripheral populations of the typical form of </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">achatina</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:Verdana;"> would have isolated and developed in the drier facies of the humid forest that individualized in the northern sector of the mountains after the arid or interpluvial period of Holocene. In addition, we find that </span><span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">A</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">togoensis</span></i><span style="font-family:Verdana;"></i></span></span><span style="font-family:Verdana;"> meets the criteria B2ab</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">(ii, iii) to categorize as “Endangered”. However, whether this latter should be considered as separate species cannot be decided at the current state of knowledge.
文摘The omnivorous fish species, <i>C. nigrodigitatus</i> feeds mainly on benthic organisms and may therefore consume contaminated food throughout its food web. This can lead to the bioaccumulation of contaminants such as trace elements in their tissues. However, fish consumption is a major pathway of human exposure to contaminants which may cause public health problems. The aim of the present study is to assess trace elements contamination in some species from the food web of <i>C. nigrodigitatus</i>. For this, 10 main food items of the silver catfish were collected at two sites from February to July 2017 and analyzed using an Atomic Absorption Spectrometer coupled with a hydride and cold vapour generator. The concentrations of trace elements varied greatly from one species to another and within each species. These values ranged from 0.007 mg/kg for Hg in C hippos to 354.84 mg/kg for Mn in <i>P. fusca</i>. The most contaminated species by trace elements were benthic organisms: <i>M. perna</i> (Cd, Pb, Hg), <i>Pagurus</i> sp. (Cr, Ni, Cu, Zn), <i>G. paradoxa</i> (As) and <i>P. fusca</i> (Mn). The average concentrations of trace elements found in species were, for the most part, above WHO standards except Hg in <i>M. perna</i> and <i>G. paradoxa</i>. The water-based bioconcentration factors (BCFw) reach 92.58 for Cd, 44.72 for Pb, 382.49 for Hg and 1514.34 for As in <i>M. perna</i>. It is therefore necessary to pay particular attention to this ecosystem and to put in place a better management plan.
文摘Green coal or bio-coal is coal produced with rich biodegradable materials, elaborated from agricultural and household residues with a high percentage of carbon. This green charcoal (fuel briquettes) is an alternative to charcoal. Well known for its contribution to greenhouse gas emissions, charcoal is one of the causes of tree felling. The valorization of waste by the manufacture of biofuels could be an alternative to the use of charcoal. The general objective of the present study is the valorization of nine biomasses from Togo as raw materials. Specifically, physico-chemical characteristics such as dehydration, acidity, and conductivity were determined. Information on the structure and composition of the biomass was found. These data on the nature of the biomass were found through the use of Fourier Transform Infrared (FTIR) and Thermogravimetry (TGA). The promising results inform on the nature of the analyzed samples and allow the selection of the best biomass which would give an important thermal conductivity for the manufacture of the briquettes, but also of the binders to be used according to the physico-chemical characteristics like the pH.
文摘The objective of this work was to determine the suitability of poultry methacompost from the 2nd methanizer of the BRIN FOUNDATION in Yaokokoroko (Bondoukou, Côte d’Ivoire), to be used in the improvement of soil fertility. The methacompost studied has a C/N ratio = 17.26, which could characterize a stable methacompost with high amending power. It also contains mineral elements Nitrogen (N) = 0.68% DM;Phosphorus (P) = 0.084% DM;Potassium (K) = 0.67% DM;Calcium (Ca) = 0.65% DM;Magnesium (Mg) = 0.15% DM. red in the standard relating to the organic amendments (NFU 44-051). The methacompost has fertilizing and amending properties and could not present any risk for vegetation and soils.
