This work investigates the influence of the type sludge on drainage, plant development, purification performances and biosolids quality. Drainage properties were measured through the frequency of clogging, the percent...This work investigates the influence of the type sludge on drainage, plant development, purification performances and biosolids quality. Drainage properties were measured through the frequency of clogging, the percentage of leachate recovered and the dryness of accumulated sludge. Plant development was measured through the density, the height and the stem diameter. Purification performance was evaluated from the reduction rate. Biosolids quality was measured after 3 months of maturation. The results show that the clogging frequencies were 9.5%;0% and 3.7%;the volume of leachate recovered was 42.2%;20.4% and 24.7% and, the dryness was 33.4%;61.1% and 52.4% for FS-ST, FS-STT and SS respectively. Plants densities were about, with densities 197.1, 171.3 and 178.3 plants/m2 in beds fed respectively with FS-ST, FS-STT and SS. Despite the high removal rates, the concentrations of pollutants in the leachates are above the Senegalese standard NS 05-061 for discharge into the environment. The biosolids are all mature with C/N and NH4+/NO3?ratios lower than 12 and 1 respectively. The biosolids are also rich in organic and mineral elements. The concentrations of Ascaris eggs are higher than the WHO recommendations. These biosolids should be stored for additional time or composted.展开更多
A domestic balloon-type digester with 1200 liters of substrate and a 700-litre gas reserve was installed at the Université Gaston Berger pilot farm, which has 4 cows. After an initial load of 1000 L of water, 90 ...A domestic balloon-type digester with 1200 liters of substrate and a 700-litre gas reserve was installed at the Université Gaston Berger pilot farm, which has 4 cows. After an initial load of 1000 L of water, 90 L of bovine rumen and 145 L of cow dung, the functional parameters of the reaction medium, i.e., temperature, pH, salinity and conductimetry, were regularly monitored at a rate of 3 tests per day until the thirtieth day, corresponding to the flame test and the start of analysis and daily loading of the biodigester. The analysis of the biogas obtained after the flame test showed us the considerable contribution of bovine hindquarters to the CH4 fraction, which reached 72.2% from the start of the production phase. As anaerobic digestion is both a complex and multiparametric process, microbiological analysis revealed the presence of several strains of bacteria in the substrate used. Among the most abundant were Escherichia coli, Klebsiella spp, non-fermentative Gram-negative bacilli and Enterococcus sp. However, the bacterial strain that interests us most in anaerobic digestion is the non-fermentative Gram-negative family. We see the identification and temporal monitoring of these families of bacteria as a major step forward in the control of anaerobic fermentation processes in the Sahelian context and in Senegal in particular.展开更多
This study addresses firstly the soil fabric variations of loose and dense compacted soil samples during a single wetting/drying cycle at suctions between 0 and 287.9 MPa using mainly the mercury intrusion porosimetry...This study addresses firstly the soil fabric variations of loose and dense compacted soil samples during a single wetting/drying cycle at suctions between 0 and 287.9 MPa using mainly the mercury intrusion porosimetry（MIP） tests.Two suction techniques were employed to apply this wide suction range：the osmotic technique for suctions less than 8.5 MPa,and the vapor equilibrium or salt solution technique for suctions higher than 8.5 MPa.Secondly,the soil water retention curves（SWRCs） were predicted by the MIP test results for both loose and dense soil samples.A reasonable correspondence between MIP results and SWRCs was found on the wetting path at lower suctions close to saturation and on drying path at higher suctions.展开更多
Bone charcoal (BC) is being developed as a treatment for decontamination of polluted water. In this study, bone charcoal was obtained by pyrolysis of cow bones and tested for the elimination of copper from aqueous sol...Bone charcoal (BC) is being developed as a treatment for decontamination of polluted water. In this study, bone charcoal was obtained by pyrolysis of cow bones and tested for the elimination of copper from aqueous solutions. The minimum time to reach the removal equilibrium by adsorption was 10 min with a maximum of copper removal equal to 9615 mg/g. Different kinetics models were applied to fit the experimental data: the pseudo second-order model correlated the results with a linear correlation coefficient equal to 1.展开更多
The coastline is one of the country’s most important environmental and economic resources. However, it is a delicate and highly coveted environ-ment on which many factors of evolution interact, both anthropogenic and...The coastline is one of the country’s most important environmental and economic resources. However, it is a delicate and highly coveted environ-ment on which many factors of evolution interact, both anthropogenic and natural. This work is concerned with the diachronic study of the coastline of the Mediterranean coast, particularly the coastal fringe at the level of Tangier Bay. In order to experimentally confirm the numerical models used and to take part in the development of an accurate, reliable and rapid decision support system for the assessment and remediation of the risks of accretion and coastal erosion, the methodology followed consists of the application of automatic analytical techniques, based on a geomatics approach, using a multi-temporal photo-interpretation, a Geographical Information System (GIS) and a computerized data analysis system (DSAS: Digital Shoreline Analysis System). The change rate will be calculated from the multi-date maps (1981-96 and 2017) using the End Point Rate (EPR). To achieve our objective, the study area was divided into three sectors from East to West: El Ghandouri Beach, Malabata Beach and the municipal square adjacent to the port. The GIS analysis of the data obtained shows that the coastline is present by location and for the three periods of comparison of the remarkable zones of erosion and sedimentation.展开更多
Background Deforestation is a widespread disturbance for neotropical freshwater ecosystems.While biodiversity declines have been associated with deforestation,its functional consequences for stream and river fish faun...Background Deforestation is a widespread disturbance for neotropical freshwater ecosystems.While biodiversity declines have been associated with deforestation,its functional consequences for stream and river fish faunas remain poorly understood.In this study,we explored how deforestation affects the different facets of the functional structure of fish communities inventoried using environmental DNA metabarcoding in 64 river and 35 stream sites of French Guiana.Specifically,we investigated how functional richness,divergence,evenness and identity of fish faunas are affected by deforestation.Results We showed that anthropogenic disturbances in French Guiana are modifying the functional diversity of freshwater fish communities.These disturbances not only affected the amount of functional traits held by the communities but also the identity of the traits and the internal structure of the functional space.Consequently,different facets of the functional diversity supported by fish assemblages were altered.In streams,deforestation did not affect the overall diversity of traits but reduced functional redundancy,underlined by a shift in functional identity towards assemblages dominated by pelagic detritivores.In contrast,river fish faunas experienced a decline in functional richness,paired with shifts in functional identity and a loss of fish species with extreme functions.Conclusions The response to deforestation differed between streams and rivers,but it supports the hypothesis that deforestation is linked to functional changes in fish assemblages.By diminishing the range of the functions in rivers or by jeopardizing the redundancy of functions in streams,deforestation could severely hamper the functioning and stability of neotropical freshwater ecosystems.展开更多
Delayed Geochemical Hazard (DGH briefly) presents the whole process of a kind of serious ecological and environmental hazard caused by sudden reactivation and sharp release of long-term accumulated pollutant from stab...Delayed Geochemical Hazard (DGH briefly) presents the whole process of a kind of serious ecological and environmental hazard caused by sudden reactivation and sharp release of long-term accumulated pollutant from stable species to active ones in soil or sediment system due to the change of physical-chemical conditions (such as temperature, pH, Eh, moisture, the concentrations of organic matters, etc.) or the decrease of environment capacity. The characteristics of DGH are discussed. The process of a typical DGH can be expressed as a nonlinear polynomial. The points where the derivative functions of the first and second orders of the polynomial reach zero, minimum and maximum are keys for risk assessment and harzard pridication.The process and mechanism of the hazard is due to the transform of pollutant among different species principally. The concepts of "total releasable content of pollutant", TRCP, and "total concentration of active specie", TCAS, are necessarily defined to describe the mechanism of DGH. The possibility of the temporal and spatial propagation is discussed. Case study shows that there exists a transform mechanism of "gradual release" and "chain reaction" among the species of the exchangeable and the bounds to carbonate, iron and manganese oxides and organic matter, thus causing the delayed geochemical hazard.展开更多
Mauritania is characterized by fast-growing fisheries that have developed over the past several decades from low levels of fishing to intense fishing and have led to severe decreases in biomass and severe signs of ove...Mauritania is characterized by fast-growing fisheries that have developed over the past several decades from low levels of fishing to intense fishing and have led to severe decreases in biomass and severe signs of overexploitation.To ensure sustainable fisheries,a primary goal of science-based fisheries policy is to provide an adequate conservation status of marine habitats that are directly,or indirectly,fundamental for the lifecycle of fish populations of commercial interest.The National Park of Banc d’Arguin has been recognized for its nursery and fish biomass export functions.In this paper,we present the economic value of the fish provisioning service of marine coastal ecosystems of the protected area.We estimated the added value of artisanal fisheries,the spatial distribution of fishing activities,the contribution of the Park to the Mauritanian fisheries and the heritage value of artisanal fisheries.Overall,the average added value for artisanal fisheries is about 43 million MRU(1 million euros)over the period 2006–2017.It mainly benefits to the ship-owners,which generates inequalities and threatens the livelihoods of the Imraguen.The spatial distribution of fishing activities and associated revenues shows high variability throughout the years,the seasons and the geographic areas,and reveals the high adaptability of Imraguen fishers.Fishing grounds are mostly located close to the shore,associated with seagrass beds,confirming the service of fish provisioning rendered by this ecosystem.Furthermore,the high productivity of seagrass beds contributes to the spill-over of biomass.The contribution of the Park to fishing activities that occur within the Mauritanian Exclusive Economic Zone is estimated to 15%,representing an added value creation of 3.2 billion MRU(71 million euros).The heritage value of the fisheries is assessed,through fishers’willingness to accept to stop their fishing activities,at 17.5 million MRU(0.4 million euros).Thus,this paper highlights the necessity of incorporating an ecosystem-based approach along with fishers’knowledge and adaptability into future conservation plan of the National Park of Banc d’Arguin and fisheries management at the local,national and regional scale.展开更多
文摘This work investigates the influence of the type sludge on drainage, plant development, purification performances and biosolids quality. Drainage properties were measured through the frequency of clogging, the percentage of leachate recovered and the dryness of accumulated sludge. Plant development was measured through the density, the height and the stem diameter. Purification performance was evaluated from the reduction rate. Biosolids quality was measured after 3 months of maturation. The results show that the clogging frequencies were 9.5%;0% and 3.7%;the volume of leachate recovered was 42.2%;20.4% and 24.7% and, the dryness was 33.4%;61.1% and 52.4% for FS-ST, FS-STT and SS respectively. Plants densities were about, with densities 197.1, 171.3 and 178.3 plants/m2 in beds fed respectively with FS-ST, FS-STT and SS. Despite the high removal rates, the concentrations of pollutants in the leachates are above the Senegalese standard NS 05-061 for discharge into the environment. The biosolids are all mature with C/N and NH4+/NO3?ratios lower than 12 and 1 respectively. The biosolids are also rich in organic and mineral elements. The concentrations of Ascaris eggs are higher than the WHO recommendations. These biosolids should be stored for additional time or composted.
文摘A domestic balloon-type digester with 1200 liters of substrate and a 700-litre gas reserve was installed at the Université Gaston Berger pilot farm, which has 4 cows. After an initial load of 1000 L of water, 90 L of bovine rumen and 145 L of cow dung, the functional parameters of the reaction medium, i.e., temperature, pH, salinity and conductimetry, were regularly monitored at a rate of 3 tests per day until the thirtieth day, corresponding to the flame test and the start of analysis and daily loading of the biodigester. The analysis of the biogas obtained after the flame test showed us the considerable contribution of bovine hindquarters to the CH4 fraction, which reached 72.2% from the start of the production phase. As anaerobic digestion is both a complex and multiparametric process, microbiological analysis revealed the presence of several strains of bacteria in the substrate used. Among the most abundant were Escherichia coli, Klebsiella spp, non-fermentative Gram-negative bacilli and Enterococcus sp. However, the bacterial strain that interests us most in anaerobic digestion is the non-fermentative Gram-negative family. We see the identification and temporal monitoring of these families of bacteria as a major step forward in the control of anaerobic fermentation processes in the Sahelian context and in Senegal in particular.
文摘This study addresses firstly the soil fabric variations of loose and dense compacted soil samples during a single wetting/drying cycle at suctions between 0 and 287.9 MPa using mainly the mercury intrusion porosimetry（MIP） tests.Two suction techniques were employed to apply this wide suction range：the osmotic technique for suctions less than 8.5 MPa,and the vapor equilibrium or salt solution technique for suctions higher than 8.5 MPa.Secondly,the soil water retention curves（SWRCs） were predicted by the MIP test results for both loose and dense soil samples.A reasonable correspondence between MIP results and SWRCs was found on the wetting path at lower suctions close to saturation and on drying path at higher suctions.
文摘Bone charcoal (BC) is being developed as a treatment for decontamination of polluted water. In this study, bone charcoal was obtained by pyrolysis of cow bones and tested for the elimination of copper from aqueous solutions. The minimum time to reach the removal equilibrium by adsorption was 10 min with a maximum of copper removal equal to 9615 mg/g. Different kinetics models were applied to fit the experimental data: the pseudo second-order model correlated the results with a linear correlation coefficient equal to 1.
文摘The coastline is one of the country’s most important environmental and economic resources. However, it is a delicate and highly coveted environ-ment on which many factors of evolution interact, both anthropogenic and natural. This work is concerned with the diachronic study of the coastline of the Mediterranean coast, particularly the coastal fringe at the level of Tangier Bay. In order to experimentally confirm the numerical models used and to take part in the development of an accurate, reliable and rapid decision support system for the assessment and remediation of the risks of accretion and coastal erosion, the methodology followed consists of the application of automatic analytical techniques, based on a geomatics approach, using a multi-temporal photo-interpretation, a Geographical Information System (GIS) and a computerized data analysis system (DSAS: Digital Shoreline Analysis System). The change rate will be calculated from the multi-date maps (1981-96 and 2017) using the End Point Rate (EPR). To achieve our objective, the study area was divided into three sectors from East to West: El Ghandouri Beach, Malabata Beach and the municipal square adjacent to the port. The GIS analysis of the data obtained shows that the coastline is present by location and for the three periods of comparison of the remarkable zones of erosion and sedimentation.
文摘Background Deforestation is a widespread disturbance for neotropical freshwater ecosystems.While biodiversity declines have been associated with deforestation,its functional consequences for stream and river fish faunas remain poorly understood.In this study,we explored how deforestation affects the different facets of the functional structure of fish communities inventoried using environmental DNA metabarcoding in 64 river and 35 stream sites of French Guiana.Specifically,we investigated how functional richness,divergence,evenness and identity of fish faunas are affected by deforestation.Results We showed that anthropogenic disturbances in French Guiana are modifying the functional diversity of freshwater fish communities.These disturbances not only affected the amount of functional traits held by the communities but also the identity of the traits and the internal structure of the functional space.Consequently,different facets of the functional diversity supported by fish assemblages were altered.In streams,deforestation did not affect the overall diversity of traits but reduced functional redundancy,underlined by a shift in functional identity towards assemblages dominated by pelagic detritivores.In contrast,river fish faunas experienced a decline in functional richness,paired with shifts in functional identity and a loss of fish species with extreme functions.Conclusions The response to deforestation differed between streams and rivers,but it supports the hypothesis that deforestation is linked to functional changes in fish assemblages.By diminishing the range of the functions in rivers or by jeopardizing the redundancy of functions in streams,deforestation could severely hamper the functioning and stability of neotropical freshwater ecosystems.
文摘Delayed Geochemical Hazard (DGH briefly) presents the whole process of a kind of serious ecological and environmental hazard caused by sudden reactivation and sharp release of long-term accumulated pollutant from stable species to active ones in soil or sediment system due to the change of physical-chemical conditions (such as temperature, pH, Eh, moisture, the concentrations of organic matters, etc.) or the decrease of environment capacity. The characteristics of DGH are discussed. The process of a typical DGH can be expressed as a nonlinear polynomial. The points where the derivative functions of the first and second orders of the polynomial reach zero, minimum and maximum are keys for risk assessment and harzard pridication.The process and mechanism of the hazard is due to the transform of pollutant among different species principally. The concepts of "total releasable content of pollutant", TRCP, and "total concentration of active specie", TCAS, are necessarily defined to describe the mechanism of DGH. The possibility of the temporal and spatial propagation is discussed. Case study shows that there exists a transform mechanism of "gradual release" and "chain reaction" among the species of the exchangeable and the bounds to carbonate, iron and manganese oxides and organic matter, thus causing the delayed geochemical hazard.
基金The study was financially supported under the contract number 3/CPMP/PNBA/2017 by the French Development Agency(AFD-Agence França),the French Facility for Global Environment(FFEM)and the Trust-Fund for the Banc d’Arguin and the Coastal&Marine Biodiversity Trust Fund(BACoMaB-Mauritania.
文摘Mauritania is characterized by fast-growing fisheries that have developed over the past several decades from low levels of fishing to intense fishing and have led to severe decreases in biomass and severe signs of overexploitation.To ensure sustainable fisheries,a primary goal of science-based fisheries policy is to provide an adequate conservation status of marine habitats that are directly,or indirectly,fundamental for the lifecycle of fish populations of commercial interest.The National Park of Banc d’Arguin has been recognized for its nursery and fish biomass export functions.In this paper,we present the economic value of the fish provisioning service of marine coastal ecosystems of the protected area.We estimated the added value of artisanal fisheries,the spatial distribution of fishing activities,the contribution of the Park to the Mauritanian fisheries and the heritage value of artisanal fisheries.Overall,the average added value for artisanal fisheries is about 43 million MRU(1 million euros)over the period 2006–2017.It mainly benefits to the ship-owners,which generates inequalities and threatens the livelihoods of the Imraguen.The spatial distribution of fishing activities and associated revenues shows high variability throughout the years,the seasons and the geographic areas,and reveals the high adaptability of Imraguen fishers.Fishing grounds are mostly located close to the shore,associated with seagrass beds,confirming the service of fish provisioning rendered by this ecosystem.Furthermore,the high productivity of seagrass beds contributes to the spill-over of biomass.The contribution of the Park to fishing activities that occur within the Mauritanian Exclusive Economic Zone is estimated to 15%,representing an added value creation of 3.2 billion MRU(71 million euros).The heritage value of the fisheries is assessed,through fishers’willingness to accept to stop their fishing activities,at 17.5 million MRU(0.4 million euros).Thus,this paper highlights the necessity of incorporating an ecosystem-based approach along with fishers’knowledge and adaptability into future conservation plan of the National Park of Banc d’Arguin and fisheries management at the local,national and regional scale.
