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

Abstract

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)