Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. T...Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. This aquifer covers an area of 250 Km2, and represents an essential water resource for Laayoun city and the periphery regions. It is heavily exploited for water supply, agriculture and industry. The freshwater-saltwater interface is affected by groundwater extraction by public supplies, irrigation wells, and domestic wells in the coastal of this aquifer. The position of the interface is controlled by several factors: these include precipitation, recharge rate, dryness, evapotranspiration, hydraulic conductivity and hydraulic head. Landward migration of the interface freshwater-saltwater often results in a significant decrease in the water resources available for coastal communities. The volume pumped by public for irrigation and the domestic usage in 2010-2011 is estimated 2.5 Mm3/year, and in 2015 about 2.91 Mm3/year only for domestic usages. The objectives of this work are to model the groundwater flow and saltwater intrusion in the coastal aquifer of Fum Al Wad, by SEAWAT-2000 program which coupled both the version of MODFLOW-2000 and MT3DMS. They are designed to simulate variable-density groundwater flow and solute transport in three dimensions. The model is calibrated for hydraulic conductivity, specific yield, porosity, and recharge rate as well as dispersivity coefficient. The result of simulation of the hydrodynamic model during the period of 1986-2015 has revealed a piezometric drawdown with 2.3 m approximately at the level of the pumping zone. Furthermore, this piezometric depression is caused by excessive pumping of the various uses of water and its corresponding that has resulted in the migration of the saltwater intrusion into freshwater with 4.3 km approximately. The simulations result for scenarios 2020 and 2030 of Fum Al Wad aquifer showed a vertical decrease of the piezometric head (about 2.5 m) in 2030, but the saltwater intrusion has advanced diagonally to reach 4.7 km under the freshwater of groundwater of this aquifer.展开更多
West African Dwarf (WAD) goats represent one of the predominant small ruminant breeds raised by resource-limited households in southern Nigeria as well as in the humid west and central Africa. This breed of goats is r...West African Dwarf (WAD) goats represent one of the predominant small ruminant breeds raised by resource-limited households in southern Nigeria as well as in the humid west and central Africa. This breed of goats is renowned for its adaptation to hot and humid environments, high fertility and prolificacy under backyard systems where they are raised almost with zero investment. On account of its contributions to household income and food security in southern Nigeria, there is the need for a detailed phenotypic and genetic characterization as well as the design of breeding strategies for its conservation through sustainable utilization. A critical challenge, however, is that there are no national breeding policies in most of the countries where WAD goats are raised. The objectives of this paper are: to review literature reports on trait-level information and estimates of genetic parameters for some economic characters of WAD goats;and to discuss a communal breeding scheme for its conservation through sustainable utilization. The presentation shows that WAD goats represent a highly diverse population, with particular reference to qualitative and performance-related traits, reflecting the role of traditional institutions in the maintenance of animal diversity in local populations. A genetic improvement programme involving dispersed open nucleus breeding scheme was discussed. The scheme involves backyard WAD goat units in villages as base population and dispersed communally managed schemes that maintain a population of bucks only, as nucleus units. Critical issues such as the definition of breeding goals by farmers, as well as communal project ownership, are emphasized. The ultimate goal of the breeding programme is to create opportunities for community-based management of WAD goat genetic resources for the benefit of backyard goat farmers in the region.展开更多
Flower-like manganese wad（MW） with high activity was synthesized via ultrasonic-assisted redox reaction of sole manganese salt MnO4-.MW was characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM...Flower-like manganese wad（MW） with high activity was synthesized via ultrasonic-assisted redox reaction of sole manganese salt MnO4-.MW was characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and X-ray photoelectron spectroscopy（XPS）.The experimental results indicate that the maximum decolorization rate of Congo red（CR） reached above 95％ within 15 min in a wide pH range from 2.0 to 6.0.Results also show that MW has excellent decolorization performance for azo dye CR which implies potential application for removing dye pollutants from industrial effluents.展开更多
The coastal plain aquifer down gradient of Wad Essaquia Elhamra(WEE),is the main source of groundwater in the arid region of Laayoune Essaquia El Hamra located in south of Morocco.The over-exploitation of this aquifer...The coastal plain aquifer down gradient of Wad Essaquia Elhamra(WEE),is the main source of groundwater in the arid region of Laayoune Essaquia El Hamra located in south of Morocco.The over-exploitation of this aquifer over the last decade for water supply,agriculture and industry led to deterioration of groundwater quality,including seawater intrusion.The objective of this study is to investigate the spatial variation of groundwater quality,and to assess the influence of sea water intrusion on the groundwater quality using hydro-chemical tools.Several measurement campaigns of physico-chemical parameters of the groundwater were performed,which shows a very high mineralization ratios versus chloride,confirming the double influence of mixing mechanisms of fresh and saline waters and the water-rock interactions.Computed seawater fraction for sampled water shows that the average mixing rate of seawater intrusion reached 10.5%,confirming the marine intrusion in the aquifer.The highest values were registered in coastal wells.In the upstream around Laayoune and the spreading area,nitrate concentrations exceed 50 mg/L which is the threshold set by the World Health Organization,revealing a high level of contamination by domestic sewage.The combination of ionic ratios and seawater fraction is a useful tool to assess marine intrusion.This study reveals that the phenomenon of marine intrusion is not the only process that dominates hydrochemistry of ground water.The high groundwater mineralization is also due to rockwater interaction associated with reverse ion exchange with clay material and anthropogenic pollutants.展开更多
文摘Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. This aquifer covers an area of 250 Km2, and represents an essential water resource for Laayoun city and the periphery regions. It is heavily exploited for water supply, agriculture and industry. The freshwater-saltwater interface is affected by groundwater extraction by public supplies, irrigation wells, and domestic wells in the coastal of this aquifer. The position of the interface is controlled by several factors: these include precipitation, recharge rate, dryness, evapotranspiration, hydraulic conductivity and hydraulic head. Landward migration of the interface freshwater-saltwater often results in a significant decrease in the water resources available for coastal communities. The volume pumped by public for irrigation and the domestic usage in 2010-2011 is estimated 2.5 Mm3/year, and in 2015 about 2.91 Mm3/year only for domestic usages. The objectives of this work are to model the groundwater flow and saltwater intrusion in the coastal aquifer of Fum Al Wad, by SEAWAT-2000 program which coupled both the version of MODFLOW-2000 and MT3DMS. They are designed to simulate variable-density groundwater flow and solute transport in three dimensions. The model is calibrated for hydraulic conductivity, specific yield, porosity, and recharge rate as well as dispersivity coefficient. The result of simulation of the hydrodynamic model during the period of 1986-2015 has revealed a piezometric drawdown with 2.3 m approximately at the level of the pumping zone. Furthermore, this piezometric depression is caused by excessive pumping of the various uses of water and its corresponding that has resulted in the migration of the saltwater intrusion into freshwater with 4.3 km approximately. The simulations result for scenarios 2020 and 2030 of Fum Al Wad aquifer showed a vertical decrease of the piezometric head (about 2.5 m) in 2030, but the saltwater intrusion has advanced diagonally to reach 4.7 km under the freshwater of groundwater of this aquifer.
文摘West African Dwarf (WAD) goats represent one of the predominant small ruminant breeds raised by resource-limited households in southern Nigeria as well as in the humid west and central Africa. This breed of goats is renowned for its adaptation to hot and humid environments, high fertility and prolificacy under backyard systems where they are raised almost with zero investment. On account of its contributions to household income and food security in southern Nigeria, there is the need for a detailed phenotypic and genetic characterization as well as the design of breeding strategies for its conservation through sustainable utilization. A critical challenge, however, is that there are no national breeding policies in most of the countries where WAD goats are raised. The objectives of this paper are: to review literature reports on trait-level information and estimates of genetic parameters for some economic characters of WAD goats;and to discuss a communal breeding scheme for its conservation through sustainable utilization. The presentation shows that WAD goats represent a highly diverse population, with particular reference to qualitative and performance-related traits, reflecting the role of traditional institutions in the maintenance of animal diversity in local populations. A genetic improvement programme involving dispersed open nucleus breeding scheme was discussed. The scheme involves backyard WAD goat units in villages as base population and dispersed communally managed schemes that maintain a population of bucks only, as nucleus units. Critical issues such as the definition of breeding goals by farmers, as well as communal project ownership, are emphasized. The ultimate goal of the breeding programme is to create opportunities for community-based management of WAD goat genetic resources for the benefit of backyard goat farmers in the region.
基金Supported by the National Science Foundation of USA（No.1067947）.
文摘Flower-like manganese wad（MW） with high activity was synthesized via ultrasonic-assisted redox reaction of sole manganese salt MnO4-.MW was characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and X-ray photoelectron spectroscopy（XPS）.The experimental results indicate that the maximum decolorization rate of Congo red（CR） reached above 95％ within 15 min in a wide pH range from 2.0 to 6.0.Results also show that MW has excellent decolorization performance for azo dye CR which implies potential application for removing dye pollutants from industrial effluents.
文摘The coastal plain aquifer down gradient of Wad Essaquia Elhamra(WEE),is the main source of groundwater in the arid region of Laayoune Essaquia El Hamra located in south of Morocco.The over-exploitation of this aquifer over the last decade for water supply,agriculture and industry led to deterioration of groundwater quality,including seawater intrusion.The objective of this study is to investigate the spatial variation of groundwater quality,and to assess the influence of sea water intrusion on the groundwater quality using hydro-chemical tools.Several measurement campaigns of physico-chemical parameters of the groundwater were performed,which shows a very high mineralization ratios versus chloride,confirming the double influence of mixing mechanisms of fresh and saline waters and the water-rock interactions.Computed seawater fraction for sampled water shows that the average mixing rate of seawater intrusion reached 10.5%,confirming the marine intrusion in the aquifer.The highest values were registered in coastal wells.In the upstream around Laayoune and the spreading area,nitrate concentrations exceed 50 mg/L which is the threshold set by the World Health Organization,revealing a high level of contamination by domestic sewage.The combination of ionic ratios and seawater fraction is a useful tool to assess marine intrusion.This study reveals that the phenomenon of marine intrusion is not the only process that dominates hydrochemistry of ground water.The high groundwater mineralization is also due to rockwater interaction associated with reverse ion exchange with clay material and anthropogenic pollutants.
