Assessing Sediment and Nutrient Transport in the Pra Basin of Ghana

Regression analysis was used to establish relationships between suspended sediment yield and nutrient export coefficient as the dependent variable, and runoff and catchment area as the independent variables. The established regression equation can be used to estimate suspended sediment or nutrient yield at any cross-section within the drainage basin with no sediment or nutrient data, if the mean annual runoff and catchment area are known. The equation can also be used to estimate the total suspended sediment and nutrient transport into the sea. The Pra basin of Ghana, which is made up of the Birim, Offin and Pra sub-basins, had PO4-P loads from mainly domestic, agricultural and commercial activities. The nutrient loads of Pra basin showed a general trend of increasing downstream. The high load of 14.6 t day-1 at Twifo-Praso is mainly due to palm oil production. Those of Dunkwa (1.98 t day-1) and Beposo (2.74 t day-1) were mainly due to domestic and commercial activities. The suspended sediment and nutrient transport into the sea are estimated by the model to be about 1.2 × 106 tonnes for suspended sediment, 792 tonnes for nitrates nitrogen, 3 kilo tonnes for ortho-phosphrous phosphate, 141 kilo tonnes for sulphate and 188 kilo tonnes for silicate.West African Journal of Applied Ecology Vol. 13 2008: pp. 45-5

Tool kits for the Sustainable Management of Ghana’s Riverine Biodiversity: an Overveiw

The Darwin Initiative funded project Tool kits for the Sustainable Management of Ghana’s Riverine Biodiversity was a collaboration between the Centre for African Wetlands at the University of Ghana, various units of the University of Ghana and the Ghana Wildlife Society. The project also involved collaborators from Burkina Faso, Nigeria, Cote d’Ivoire, Togo and Benin. The project aimed to address the impediments that remain for Ghana (and its neighbouring countries) in applying the Ecosystem Approach (EA) to riverine wetland management and the delivery of the Convention on Biodiversity (CBD). Priority needs were identified as taxonomic capacity building, a contemporary assessment of the status of aquatic biodiversity in Ghana, the development of practical management tools for rivers and increased engagement of stakeholders in decision-making together with an enhanced environmental awareness throughout Ghanaian society. These were addressed in this project by regional and local staff training, reporting on the current status of aquatic communities, the production of educational and taxonomic resources for a range of users, the development of a set of nested indicators of ecosystem health adapted for use at various levels, and the production of a policy document outlining the means of applying the EA in the management of Ghana’s rivers

Land-based sources of pollution and environmental quality of Weija Lake

A survey of land-based sources of pollution was undertaken in the catchment area of Weija Lake. Activities that may influence the quality of the environment, and the sources, amounts and effects of the pollution of the water body were assessed. Water and precipitation chemistry showed that Na:Ca (0.48) and Na:K (2.0) ratios were influenced by individual pollution and terrestrial dust. However, Na:Cl (0.74) and Na:Mg (1.06) ratios suggest an oceanic origin of these ions. Mean phosphate load of 100.4 t yr-1 for Weija Lake was enough for eutrophication to take place. There was an input of 12.42 t yr-1 from settlements, and 9.072 t yr-1 from fertilizer input through runoff, and then the Densu River also had an input of 1,217.6 t yr-1 into the Weija Lake. Similarly, the sources of pollution from settlements, runoff from fertilizer input from the River Densu revealed that the major contributor of nutrients and BOD into the Weija Lake is the River Densu. This can be attributed mainly to the dumping of garbage, solid and liquid wastes upstream of the River Densu. The high mean nitrogen load of 3,003 t yr-1 can also be attributed to organic nitrogen input from domestic and agricultural origin. This was due to the high seasonal trend of nitrate in the months of March and May as a result of the main ploughing periods for farming in the Weija Lake catchment area, where fertilizer is applied. Preliminary recommendations and remedial measures to solve the problems as assessed, and proposed for preventive remedial and/or control measures were made. (Journal of the Ghana Science Association: 2001 3(3): 100-108

Total petroleum content and polycyclic aromatic hydrocarbon levels in soil and groundwater at the site of a fuel service station in Accra.

Analysis of Total Petroleum Content (TPC) and Polycyclic Aromatic Hydrocarbon (PAH) in soil and ground-water at the site of a Fuel Service Station indicated leakage of petroleum products from the underground storage tanks buried 3.6 km below the surface. The leakage resulted in contamination of areas within a 60 m radius. In the TPC profiles, distinct peak corresponding to diesel oil occurred between 5 and 17 min; while a hump charac-teristic of mineral oil occurred between 17 and 25 min. In the PAH profiles, 18 compounds were identified and quantified by means of gas chromatography. The TPC levels ranged between 0.918 - 21.9 μg/L for groundwater and 44.1 - 894 mg/kg for soil. The levels of PAHs were low and HM-PAHs were not detected. The total PAH levels varied between 20.93 - 51.85 μg/L for groundwater and 2.07 - 6.5 ng/kg ww for soil. The levels of LM-PAHs were above the International standard of 200 ng/L, while BaP levels were 710 ng/L (indicative of carcino-genic effects). Naphthalene was found to be abundant in the groundwater. Journal of Applied Science and Technology Vol. 13 (1 & 2) 2008: pp. 64-7