Investigations were conducted over a six-month period on leachate which continuously egresses from a “natural attenuation” landfill site into a fragile ecosystem in the Accra Metropolis, Ghana. Most physico-chemical...Investigations were conducted over a six-month period on leachate which continuously egresses from a “natural attenuation” landfill site into a fragile ecosystem in the Accra Metropolis, Ghana. Most physico-chemical, oxygen demand parameters and nutrient contents were within permissible limits but Total Dissolved Solids (1124 - 13200 mg/l), conductivity (7960 - 24890 μS/cm), Mn (0.12 - 0.94 mg/l), Ca2+ (160 - 356 mg/l) and, more especially chloride contents (1030 - 2967 mg/l) far exceeded respective World Health Organisation (WHO) limits for effluent discharge into the natural environment. Multivariate statistics using Principal Component Analysis (PCA) and Cluster Analysis (CA) suggest significant concentrations of Ca2+, Cl-, and to a lesser extent Zn, Cd, Mn and PO42- relative to the river water samples. Because the landfill was abandoned recently (in 2009), degradation and other breakdown processes of waste material may only have just began, suggesting that the uncontrolled and continuous discharge of chloride and some heavy metal-laden leachate could, in the long-term, substantially impact negatively on the Ramsar Densu wetland and surrounding water bodies, soil and nearby marine ecosystem.展开更多
For four centuries now, southern Ghana has been known to be seismically active, and there is no clear geological explanation for the cause of the seismicity. By evaluating new field data and information with re-interp...For four centuries now, southern Ghana has been known to be seismically active, and there is no clear geological explanation for the cause of the seismicity. By evaluating new field data and information with re-interpreted historical earthquake data of southern Ghana, the nature of the seismicity of southern Ghana has been elucidated. The mutual connection between the earthquake epicentres and the remote causes by Mid-Atlantic transform faults and fracture zones has been established. The seismic regions of southern Ghana have been linked separately to tectonic faults and activities of the St. Paul’s and Romanche transform-fracture zone systems offshore in the Gulf of Guinea to onshore. It is concluded that the seismicity of southern Ghana is due to tectonic activities of the St. Paul’s and Romanche transform-fracture systems. The Accra region earthquakes originate from reactivation of faults in the Romanche transform-fracture zone, and propagate onshore through Accra and environs. The Axim region earthquakes come from reactivated faults linked to the St Paul’s fracture zone, which go through southern Cote D’Ivoire to Ghana. Seismotectonic movements along the St Paul’s transform and fracture zones have quieted since 1879. But movement along the Romanche Transform fault and Fracture zone is active, causing ongoing seismicity of southern Ghana.展开更多
文摘Investigations were conducted over a six-month period on leachate which continuously egresses from a “natural attenuation” landfill site into a fragile ecosystem in the Accra Metropolis, Ghana. Most physico-chemical, oxygen demand parameters and nutrient contents were within permissible limits but Total Dissolved Solids (1124 - 13200 mg/l), conductivity (7960 - 24890 μS/cm), Mn (0.12 - 0.94 mg/l), Ca2+ (160 - 356 mg/l) and, more especially chloride contents (1030 - 2967 mg/l) far exceeded respective World Health Organisation (WHO) limits for effluent discharge into the natural environment. Multivariate statistics using Principal Component Analysis (PCA) and Cluster Analysis (CA) suggest significant concentrations of Ca2+, Cl-, and to a lesser extent Zn, Cd, Mn and PO42- relative to the river water samples. Because the landfill was abandoned recently (in 2009), degradation and other breakdown processes of waste material may only have just began, suggesting that the uncontrolled and continuous discharge of chloride and some heavy metal-laden leachate could, in the long-term, substantially impact negatively on the Ramsar Densu wetland and surrounding water bodies, soil and nearby marine ecosystem.
文摘For four centuries now, southern Ghana has been known to be seismically active, and there is no clear geological explanation for the cause of the seismicity. By evaluating new field data and information with re-interpreted historical earthquake data of southern Ghana, the nature of the seismicity of southern Ghana has been elucidated. The mutual connection between the earthquake epicentres and the remote causes by Mid-Atlantic transform faults and fracture zones has been established. The seismic regions of southern Ghana have been linked separately to tectonic faults and activities of the St. Paul’s and Romanche transform-fracture zone systems offshore in the Gulf of Guinea to onshore. It is concluded that the seismicity of southern Ghana is due to tectonic activities of the St. Paul’s and Romanche transform-fracture systems. The Accra region earthquakes originate from reactivation of faults in the Romanche transform-fracture zone, and propagate onshore through Accra and environs. The Axim region earthquakes come from reactivated faults linked to the St Paul’s fracture zone, which go through southern Cote D’Ivoire to Ghana. Seismotectonic movements along the St Paul’s transform and fracture zones have quieted since 1879. But movement along the Romanche Transform fault and Fracture zone is active, causing ongoing seismicity of southern Ghana.
